msm: clock-9615: Vote for VDD_DIG via the new voltage corner regulator

Vote on the new voltage corner regulator (that indirectly
sets the voltage on PM8018_S1) instead of voting for a
specific voltage on S1.

Change-Id: I437c6ad29dacd1eeae064444c38c4175428a6699
CRs-Fixed: 354458
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: David Collins <collinsd@codeaurora.org>