drivers: thermal: bcl: Update the threshold conversion

Ibat and vbat threshold registers were bit shifted in earlier BCL
peripheral and starting PMIC7, the bit shift is not there. So remove
the ADC to ibat/vbat and vice versa conversion to accommodate this.

Change-Id: I45c3b389925c9f6853d14cd8d7aaee3de5310bdf
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>