arm64: rockchip: Force CONFIG_PM on Rockchip systems

[ Upstream commit 7db7a8f5638a2ffe0c0c0d55b5186b6191fd6af7 ]

A number of the Rockchip-specific drivers (IOMMU, display controllers)
are now assuming that CONFIG_PM is set, and may completely misbehave
if that's not the case.

Since there is hardly any reason for this configuration option not
to be selected anyway, let's require it (in the same way Tegra already
does).

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>