reg_cap.phy_id is extracted from WMI event and could be an unexpected value
in case some errors happen. As a result out-of-bound write may occur to
soc->hal_reg_cap. Fix it by validating reg_cap.phy_id before using it.

This is found during code review.

Compile tested only.
Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230830020716.5420-1-quic_bqiang@quicinc.com