power: regulator: qcom-rpmh: correctly map pmic mode

power: regulator: qcom-rpmh: correctly map pmic mode

Currently we don't properly map between the regulator mode ID enum and
the appropriate register values in the mode map, as a result we always
unintentionally vote for retention mode if we actually attempt to set
it. In the set_mode path we did find the appropriate entry in the mode
map but we wrote the id instead of the register values. Clean this up
and properly map id -> mode and vice versa.

Link: https://patch.msgid.link/20260108-rpmh-regulator-fixes-v1-6-d1b5b300b665@linaro.org
Signed-off-by: Casey Connolly <casey.connolly@linaro.org>