microblaze: Remove saving and restoring before calling signal code

Saving is done in SAVE_STATE macros that's why another save discard
previous saved value.

This change has no effect to normal programs because they ends in any exception
and they are killed. On the other side has effect on debugging.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

arch/microblaze/kernel/entry.S

@@ -711,15 +711,11 @@ C_ENTRY(ret_from_exc):
 	 * (in a possibly modified form) after do_signal returns.
 	 * store return registers separately because this macros is use
 	 * for others exceptions */
-	swi	r3, r1, PTO + PT_R3;
-	swi	r4, r1, PTO + PT_R4;
 	la	r5, r1, PTO;		/* Arg 1: struct pt_regs *regs */
 	add	r6, r0, r0;		/* Arg 2: sigset_t *oldset */
 	addi	r7, r0, 0;		/* Arg 3: int in_syscall */
 	bralid	r15, do_signal;	/* Handle any signals */
 	nop;
-	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
-	lwi	r4, r1, PTO+PT_R4;
 
 /* Finally, return to user state.  */
 1:	swi	r0, r0, PER_CPU(KM);	/* Now officially in user state. */