power: qpnp-qg: Update the qg_esr_mod_count based on fifo-length

Shorter FIFO updates lead to frequent ESR estimation. Avoid this
by updating the esr-estimation frequency based on fifo-length.

Change-Id: I26b3ad75c88d5cbf97766e86710f677e11a77df1
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>