firmware: arm_scmi: Add clock management to the SCMI power domain

Clocks requiring non-atomic contexts are supported by the generic clock
PM layer since commit 0bfa0820 ("PM: clk: make PM clock layer
compatible with clocks that must sleep"). That means we can have
SCMI-based clocks be managed by the SCMI power domain now.

Link: https://lore.kernel.org/r/5q88n947-pon-4940-3or6-s54o4r361o5s@onlyvoer.pbz


Tested-by: Dien Pham <dien.pham.ry@renesas.com>
Reviewed-by: Gaku Inami <gaku.inami.xh@renesas.com>
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>