[arch][arm] Enable caches early if WITH_KERNEL_VM is set

Spinlocks and atomic operations may not work on uncached memory. If
WITH_KERNEL_VM is set, the mmu is enabled early (with cached) mappings,
but unless the caches are also enabled in SCTLR they may not work.

Also, initialize SCTLR on secondary cpus.

Change-Id: Icaa186ed582be0df7cb531731334239ea1e19f2e
Signed-off-by: Arve Hjønnevåg <arve@android.com>

arch/arm/arm/start.S

@@ -48,6 +48,11 @@ arm_reset:
 	/* i/d cache disable, mmu disabled */
 	bic		r12, #(1<<12)
 	bic		r12, #(1<<2 | 1<<0)
+#if WITH_KERNEL_VM
+	/* enable caches so atomics and spinlocks work */
+	orr		r12, r12, #(1<<12)
+	orr		r12, r12, #(1<<2)
+#endif
 	mcr		p15, 0, r12, c1, c0, 0
 
 	/* calculate phys offset */