When SoC first boots up, we should invalidate the cache but not flush it.
We can use the same function for invalid and flush mostly, with a wrapper.

Invalidating large cache can ben slow on emulator, so we postpone doing
so until I-cache is enabled, and before enabling D-cache.

Signed-off-by: York Sun <yorksun@freescale.com>
CC: David Feng <fenghua@phytium.com.cn>