Add support for the Amlogic SM1 platform for the current MPEG1 & MPEG2
support.

The SM1 family, very close to the G12A SoCs, has a slighly different power
management control, thus needing a separate compatible and family id.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>