icnss: Add support of monitoring vph_pwr

Add support of monitoring runtime phone power. Driver configures two
threshold values and receives notifications when phone power
crosses either high or low threshold. Driver then sends indication to
WLAN FW, which will vote for different regulator power mode based on the
indication.

CRs-Fixed: 1050198
Change-Id: I0614286f1b2a3446d40ad4d82e24a6e8f91069e1
Signed-off-by: Yuanyuan Liu <yuanliu@codeaurora.org>