power: qpnp-fg-gen3: use the CC_STEP and CC_STEP_SEL properties

Add support for the CC_STEP and CC_STEP_SEL properties in the BMS power
supply. These properties will be used to communicate the future charge
currents for time to full calculations.

Change-Id: I44087b42b31800d1885bdaf1f38815c8756bc9a8
Signed-off-by: Nicholas Troast <ntroast@codeaurora.org>
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>