ARM: multi_v7_defconfig: Enable Rockchip generic power domain.

In order to meet high performance an low power requirement for Rockchip
enable the power domain support. The patch also fixes a drm/kms issue,
driver deferring untils power-domains are available)

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>