power: qpnp-fg: reduce the probe time of driver

Currently when the fuel gauge driver probes, hardware init and
updating SRAM parameters consumes more time because of the
internal SRAM access adding up to the delay.

Move these functions from the probe to a scheduled work so that
the driver probe function can finish up early improving up the
boot time.

Also, move the fg_hw_init routine to the front of the
initialization work in order to ensure that the hardware gets
initialized before the SRAM parameters are read.

CRs-Fixed: 835416
Change-Id: I410be1c2e9093b0f238b2affcee0f7c694a3eaee
Signed-off-by: Jie Cheng <rockiec@codeaurora.org>
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>