[POWERPC] Remove _get_SP

We already have an inline __get_SP, no need for yet another one.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/kernel/misc_32.S

@@ -734,10 +734,6 @@ _GLOBAL(abs)
 	sub	r3,r3,r4
 	blr
 
-_GLOBAL(_get_SP)
-	mr	r3,r1		/* Close enough */
-	blr
-
 /*
  * Create a kernel thread
  *   kernel_thread(fn, arg, flags)