uboot-imx

arc: cache - utilize IO coherency (AKA IOC) engine

With release of ARC HS38 v2.1 new IO coherency engine could be built-in
ARC core. This hardware module ensures coherency between DMA-ed data
from peripherals and L2 cache.

With L2 and IOC enabled there's no overhead for L2 cache manual
maintenance which results in significantly improved IO bandwidth.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>