arm64/efi: Make strrchr() available to the EFI namespace

libfdt gained a new dependency on strrchr, so make it available to the
EFI namespace before we update libfdt.

Thanks to Ard for providing this fix.

Cc: Catalin Marinas <[e-mail]>
Acked-by: Ard Biesheuvel <[e-mail]>
Acked-by: Will Deacon <[e-mail]>
Signed-off-by: Rob Herring <[e-mail]>

arch/arm64/kernel/image.h

···
 __efistub_strnlen		= KALLSYMS_HIDE(__pi_strnlen);
 __efistub_strcmp		= KALLSYMS_HIDE(__pi_strcmp);
 __efistub_strncmp		= KALLSYMS_HIDE(__pi_strncmp);
+__efistub_strrchr		= KALLSYMS_HIDE(__pi_strrchr);
 __efistub___flush_dcache_area	= KALLSYMS_HIDE(__pi___flush_dcache_area);
 
 #ifdef CONFIG_KASAN

arch/arm64/lib/strrchr.S

···
 	b	1b
 2:	mov	x0, x3
 	ret
-ENDPROC(strrchr)
+ENDPIPROC(strrchr)