ARM: 7442/1: Revert "remove unused restart trampoline"

This reverts commit fa18484d0947b976a769d15c83c50617493c81c1.

We need the restart trampoline back so that we can revert a related
problematic patch 6b5c8045ecc7e726cdaa2a9d9c8e5008050e1252 ("arm: new
way of handling ERESTART_RESTARTBLOCK").

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 4928d89..3647170 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -820,6 +820,8 @@
 	 */
 	memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
 	       sigreturn_codes, sizeof(sigreturn_codes));
+	memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
+	       syscall_restart_code, sizeof(syscall_restart_code));
 
 	flush_icache_range(vectors, vectors + PAGE_SIZE);
 	modify_domain(DOMAIN_USER, DOMAIN_CLIENT);