plat: imx8mm: add basic imx8mm support

i.MX8MM is a new soc of the i.MX8M family, this patch
add the basic support for i.MX8MM. further code optimization
needed. WAIT mode support is currently disabled, will be enabled
later.

Signed-off-by: Bai Ping <ping.bai@nxp.com>
(cherry picked from commit 6aafe1fcd7296eded1163d919b6ce018487e8645)

Conflicts:
	plat/imx/imx8mq/sip_svc.c
9 files changed