xtensa: drop bcopy implementation

bcopy is not exported and there's no in-tree users of this function.
Drop it.

Signed-off-by: Max Filippov <[e-mail]>

arch/xtensa/include/asm/string.h

···
 extern void *memmove(void *__dest, __const__ void *__src, size_t __n);
 extern void *__memmove(void *__dest, __const__ void *__src, size_t __n);
 
-/* Don't build bcopy at all ...  */
-#define __HAVE_ARCH_BCOPY
-
 #if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
 
 /*

arch/xtensa/lib/memcopy.S

···
 ENDPROC(__memcpy)
 
 /*
- * void bcopy(const void *src, void *dest, size_t n);
- */
-
-ENTRY(bcopy)
-
-	abi_entry_default
-	# a2=src, a3=dst, a4=len
-	mov	a5, a3
-	mov	a3, a2
-	mov	a2, a5
-	j	.Lmovecommon	# go to common code for memmove+bcopy
-
-ENDPROC(bcopy)
-
-/*
  * void *memmove(void *dst, const void *src, size_t len);
  *
  * This function is intended to do the same thing as the standard