power: qpnp-qg: add support for TTF and TTE features

Time to full(TTF) and Time to empty(TTE) algorithms are supported
through fg-alg.c. Add the necessary initialization and callback
functions to qg driver to support those algorithms.

CRs-Fixed: 2254530
Change-Id: I4c400b749aa2b6fb270ab38e8a294ce69b0e20d7
Signed-off-by: Vamshi Krishna B V <vbv@codeaurora.org>