clock-alpha-pll: Enhance handoff to configure rate and outputs

Some PLLs have pre-configured rate upon boot. Others require handoff
to configure it. Add support for rate configuration based on whether
rate is pre-set. Add output configuration for PLLs that we config.

Change-Id: Ia566c09016323cc8c1299a9180d6e7176e726f78
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>