ARM: allow CONFIG_GICV* not to be defined

There are ARM SoCs (such as the BCM2837) do not contain an ARM GIC. Fix
the ARMv8 CPU startup code to compile in this case.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

arch/arm/cpu/armv8/start.S

@@ -202,14 +202,14 @@ WEAK(lowlevel_init)
 	mov	x29, lr			/* Save LR */
 
 #ifndef CONFIG_ARMV8_MULTIENTRY
+#if defined(CONFIG_GICV2) || defined(CONFIG_GICV3)
 	/*
 	 * For single-entry systems the lowlevel init is very simple.
 	 */
 	ldr	x0, =GICD_BASE
 	bl	gic_init_secure
-
+#endif
 #else /* CONFIG_ARMV8_MULTIENTRY is set */
-
 #if defined(CONFIG_GICV2) || defined(CONFIG_GICV3)
 	branch_if_slave x0, 1f
 	ldr	x0, =GICD_BASE