qcom: smb1355: restart charging after bat-discharge

SMB1355 is designed to have a minimum charging current of 500mA,
below which charging will be disabled and remain so even after
the current rise above.

Set to keep attempting re-enabling of charging until charging is
disabled by master or input is unplugged. Make the retry interval
250ms.

Change-Id: I348fe80023186dea29cb9142404f2c46a216ed37
Signed-off-by: Harry Yang <harryy@codeaurora.org>