disp: msm: register rotator platform driver after genpd init

Due to power-domain, if rotator driver is registered early,
probe might get deferred several times and get stuck
indefinitely. So, this change adds driver registration
after genpd init to handle such cases.

Change-Id: I8dcb640d0ab0cdf0818cbce1b1fb460c28d8b9e7
Signed-off-by: Yashwanth <yvulapu@codeaurora.org>