This patch adds Keystone2 K2E SOC specific code to support
MSMC cache coherency. Also create header file for msmc to hold
its API.

Acked-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Hao Zhang <hzhang@ti.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>