arm64: Update memcpy_{from, to}io() helpers

At early U-Boot stage, before relocation, MMU is not yet configured
and disabled. DDR may not be configured with the correct memory
attributes (can be configured in MT_DEVICE instead of MT_MEMORY).

In this case, usage of memcpy_{from, to}io() may leads to synchronous
abort in AARCH64 in case the normal memory address is not 64Bits aligned.

To avoid such situation, forbid usage of normal memory cast to (u64 *) in
case MMU is not enabled.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Cc: mark.kettenis@xs4all.nl
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

include/cpu_func.h

@@ -59,6 +59,7 @@ int dcache_status(void);
 void dcache_enable(void);
 void dcache_disable(void);
 void mmu_disable(void);
+int mmu_status(void);
 
 /* arch/$(ARCH)/lib/cache.c */
 void enable_caches(void);