Add the subtype and compatible strings for PM8937.

The PM8937 is found in various SoCs, including MSM8917, MSM8937,
MSM8940 and APQ variants.
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Signed-off-by: Dang Huynh <danct12@riseup.net>
Link: https://lore.kernel.org/r/20231121-pm8937-v2-1-b0171ab62075@riseup.netSigned-off-by: Lee Jones <lee@kernel.org>