wcnss: Proxy vote for Iris regulators on behalf of Riva

This patch includes the following changes,
a. Proxy vote for Iris regulators on behalf of Riva.
b. During SSR power-on, vote for Iris regulators just like in
   cold boot.
c. Remove wcnss_riva.h, it was meant to be local to platform driver.
d. Make WCNSS platform driver part of kernel

Change-Id: Ied1f91297305469a0e4d9e524a03b49e1f600852
Signed-off-by: Sameer Thalappil <sameert@codeaurora.org>