power: smb1351: fix parallel mode i2c errors from incorrect check

Currently the smb1351-charger driver checks for the presence of the
smb1351 chip in the smb1351_parallel_set_chg_present function regardless
of whether or not the primary charger is calling it to notify of
presence or removal. This is incorrect, as the check will always fail
upon removal if the VDDCAP pin on the primary charger falls fast enough
and puts the smb1351 parallel charger in suspend. This causes subsequent
parallel charging enablements to fail to run the setup routines, and
thus fail enabling parallel charger altogether.

Fix this by only checking for smb1351 chip presence upon the primary
charger notifying the driver of presence, and not upon removal.

CRs-Fixed: 877809
Change-Id: Iac226309286f9169963f5bea07648074415cb4d3
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>