power: qpnp-smbcharger: add debug mask for logging

The charger driver does a lot of its configuration at boot time.
Sometimes dynamic debug is not enough to allow the user to configure all
the relevant functions early enough to debug issues that occur early in
the driver initialization.

To address this, add a debug mask as a module parameter to allow users
to enable a wide swath of charger logs at boot time by modifying the
kernel command line.

Additionally, change all the pr_err into dev_err for consistency.

Change-Id: I146c9880b5cc579ff478c3045dea62dfc8655e14
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>