msm: sde: add minimum bus vote prior to power/clock enable

Minimum bus vote is required for sdm845 prior to power
and clock enable. Add minimum bus vote request to footswitch
control before turning on regulator.

CRs-Fixed: 2009709
Change-Id: I29a7d81042c28bf715c3fc1059fd9d2ca584bd3d
Signed-off-by: Alan Kwong <akwong@codeaurora.org>