x86/lib: Include <asm/misc.h> to fix a missing prototypes warning at build time

Signed-off-by: Anuradha Weeraman <anuradha@debian.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230103034637.74679-1-anuradha@debian.org

arch/x86/lib/misc.c

 // SPDX-License-Identifier: GPL-2.0
+#include <asm/misc.h>
+
 /*
  * Count the digits of @val including a possible sign.
  *