crypto: x86/sha1-avx2 - Fix RBP usage

Using RBP as a temporary register breaks frame pointer convention and
breaks stack traces when unwinding from an interrupt in the crypto code.

Use R11 instead of RBP.  Since R11 isn't a callee-saved register, it
doesn't need to be saved and restored on the stack.

Reported-by: Eric Biggers <ebiggers@google.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Eric Biggers <ebiggers@google.com>
Acked-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/x86/crypto/sha1_avx2_x86_64_asm.S

@@ -89,7 +89,7 @@
 #define	REG_RE	%rdx
 #define	REG_RTA	%r12
 #define	REG_RTB	%rbx
-#define	REG_T1	%ebp
+#define	REG_T1	%r11d
 #define	xmm_mov	vmovups
 #define	avx2_zeroupper	vzeroupper
 #define	RND_F1	1
@@ -637,7 +637,6 @@ _loop3:
 	ENTRY(\name)
 
 	push	%rbx
-	push	%rbp
 	push	%r12
 	push	%r13
 	push	%r14
@@ -673,7 +672,6 @@ _loop3:
 	pop	%r14
 	pop	%r13
 	pop	%r12
-	pop	%rbp
 	pop	%rbx
 
 	ret