refactor(arm): remove unused global

Removed unused global from the assembly file.

Change-Id: I17ab70aa888af27865a9fb4436495197f460780f
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/plat/arm/board/common/rotpk/arm_dev_rotpk.S b/plat/arm/board/common/rotpk/arm_dev_rotpk.S
index 06e2a06..a7fadf6 100644
--- a/plat/arm/board/common/rotpk/arm_dev_rotpk.S
+++ b/plat/arm/board/common/rotpk/arm_dev_rotpk.S
@@ -14,7 +14,6 @@
 #endif
 
 	.global arm_rotpk_header
-	.global arm_rotpk_header_end
 	.section .rodata.arm_rotpk_hash, "a"
 
 arm_rotpk_header: