power: qpnp-fg-gen4: Fix ESR timer initialization

Currently, while parsing the ESR charging and discharging timers
from the device tree, they're initialized to -EINVAL only if the
parsing function returns an error. Since the default values for
ESR timers are set to 0, fg_set_esr_timer() when called can set
the timers to 0 when it is not supposed to. Fix it.

CRs-Fixed: 2280822
Change-Id: I59bcc627fa836adfef210890e9019dc6c04bb614
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>