power: qpnp-charger: fix charging timer

The driver miscalculated the time in minutes. Fix the way it calculates
the value to program for the expected charger timer.

Moreover, before programming a new timer value, the timer had to be
disabled. Update the driver to do this. While at it, fix the register
definitions for CHGR_TCHG_MAX_EN and CHGR_TTRKL_MAX_EN.

Change-Id: I0c798aecf13e2186a9e0684f3168bf16e65c27b6
CRs-Fixed: 575809
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>