power: smb5: Ensure WLS FCC_MAIN vote is set at startup

It is observed that when WLS is attached at bootup, if the SMB1390
driver probes after the SMB5 driver, the WLS_PL_CHARGING_VOTER's vote
never gets set as the "charge_pump_master" power supply (PSY) that the
SMB1390 driver creates isn't available when the DC plugin handler
executes. As a workaround, cast this vote once the PSY comes up and
starts sending notifications.

Change-Id: Ia14cd21fec335b66bdcaa96f1bcfa7febfae225d
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>