regulator: cpr3-regulator: update BHS->LDO programming sequence

Hardware guidelines suggest that it's acceptable to program the
LDO output to the lower value of the max supported LDO voltage and
VDD_APCC minus LDO headroom as the first step of cluster BHS to
LDO switch. Update cpr3_regulator_config_ldo() to reflect this.

Change-Id: I05d6fd5546a650eebc0ea2d59ca85e5d24d51263
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>