powerpc: do not fixup NULL ptrs

The fixup routine must not fixup NULL pointers.
Problem can be seen by
 char *testfun(void) __attribute__((weak));
 char *(*myfun)(void) = testfun;

Then add
  printf("myfun:%p, &myfun:%p\n", myfun, &myfun);
before relocation and after relocation.
myfun should be NULL in both cases but it is not.
Signed-off-by: NJoakim Tjernlund <Joakim.Tjernlund@transmode.se>

arch/powerpc/cpu/74xx_7xx/start.S

@@ -709,10 +709,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 /* clear_bss: */
 	/*

arch/powerpc/cpu/mpc512x/start.S

@@ -613,10 +613,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/mpc5xx/start.S

@@ -453,10 +453,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/mpc5xxx/start.S

@@ -668,10 +668,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/mpc8220/start.S

@@ -641,10 +641,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/mpc824x/start.S

@@ -583,10 +583,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/mpc8260/start.S

@@ -904,10 +904,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/mpc83xx/start.S

@@ -952,10 +952,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 #endif
 

arch/powerpc/cpu/mpc85xx/start.S

@@ -1037,10 +1037,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/mpc86xx/start.S

@@ -727,10 +727,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 /* clear_bss: */
 	/*

arch/powerpc/cpu/mpc8xx/start.S

@@ -584,10 +584,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*

arch/powerpc/cpu/ppc4xx/start.S

@@ -1608,10 +1608,12 @@ in_ram:
 	beq	4f
 3:	lwzu	r4,4(r3)
 	lwzux	r0,r4,r11
+	cmpwi	r0,0
 	add	r0,r0,r11
 	stw	r10,0(r3)
+	beq-	5f
 	stw	r0,0(r4)
-	bdnz	3b
+5:	bdnz	3b
 4:
 clear_bss:
 	/*