arm64: klib: Optimised string functions

This patch introduces AArch64-specific string functions (strchr,
strrchr).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile
index 2fce139..59acc0e 100644
--- a/arch/arm64/lib/Makefile
+++ b/arch/arm64/lib/Makefile
@@ -2,4 +2,5 @@
 		   strncpy_from_user.o strnlen_user.o clear_user.o	\
 		   copy_from_user.o copy_to_user.o copy_in_user.o	\
 		   copy_page.o clear_page.o				\
-		   memchr.o memcpy.o memmove.o memset.o
+		   memchr.o memcpy.o memmove.o memset.o			\
+		   strchr.o strrchr.o