power: qpnp-fg-gen3: fix variable range overflow

cc_soc calculation might result in variable overflow
for larger value of cc_soc, update/typecast all the
variables to 64-bit during calculations.

Change-Id: Ic137fb5f258ae83f70e88b1858a8ebf2b9d1a4c1
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>