elf: arm: Add a few ARM relocation types

Rather than hard-coding the relocation type, add it to the ELF header file
and use it from there.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/arch/arm/lib/relocate_64.S b/arch/arm/lib/relocate_64.S
index 5c51cae..242e56e 100644
--- a/arch/arm/lib/relocate_64.S
+++ b/arch/arm/lib/relocate_64.S
@@ -10,6 +10,7 @@
 
 #include <asm-offsets.h>
 #include <config.h>
+#include <elf.h>
 #include <linux/linkage.h>
 #include <asm/macro.h>
 
@@ -47,7 +48,7 @@
 	ldp	x0, x1, [x2], #16	/* (x0,x1) <- (SRC location, fixup) */
 	ldr	x4, [x2], #8		/* x4 <- addend */
 	and	x1, x1, #0xffffffff
-	cmp	x1, #1027		/* relative fixup? */
+	cmp	x1, #R_AARCH64_RELATIVE
 	bne	fixnext
 
 	/* relative fix: store addend plus offset at dest location */