x86/uaccess: Remove ELF function annotation from copy_user_handle_tail()

After an objtool improvement, it's complaining about the CLAC in
copy_user_handle_tail():

  arch/x86/lib/copy_user_64.o: warning: objtool: .altinstr_replacement+0x12: redundant UACCESS disable
  arch/x86/lib/copy_user_64.o: warning: objtool:   copy_user_handle_tail()+0x6: (alt)
  arch/x86/lib/copy_user_64.o: warning: objtool:   copy_user_handle_tail()+0x2: (alt)
  arch/x86/lib/copy_user_64.o: warning: objtool:   copy_user_handle_tail()+0x0: <=== (func)

copy_user_handle_tail() is incorrectly marked as a callable function, so
objtool is rightfully concerned about the CLAC with no corresponding
STAC.

Remove the ELF function annotation.  The copy_user_handle_tail() code
path is already verified by objtool because it's jumped to by other
callable asm code (which does the corresponding STAC).
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/6b6e436774678b4b9873811ff023bd29935bee5b.1563413318.git.jpoimboe@redhat.com

arch/x86/lib/copy_user_64.S

@@ -239,7 +239,7 @@ copy_user_handle_tail:
 	ret
 
 	_ASM_EXTABLE_UA(1b, 2b)
-ENDPROC(copy_user_handle_tail)
+END(copy_user_handle_tail)
 
 /*
  * copy_user_nocache - Uncached memory copy with exception handling