power: qpnp-smbcharger: do not disable parallel charging during hotswap

Currently the parallel charging algorithm stops if the battery charging
stops. However, this can create issues with hotswap. When turning on and
off the parallel charger without a battery, any delay in raising the
input current of the primary charger with the secondary charger turned
off could cause the device to UVLO.

To fix this, try to not disable the parallel charger when it's active
and there is no battery present. Also, allow the input current to rise
during a hotswap so that if parallel charging does need to be disabled
for a different reason, the main charger can still recover all of its
ICL.

Change-Id: I97e19c792337436389d0c9b4931162a44ac62a15
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>