dt-bindings: regulator: Add compatible for pmg1110

Add compatible string for pmg1110 pmic.

Signed-off-by: Satya Priya <quic_c_skakit@quicinc.com>
Link: https://lore.kernel.org/r/1637668167-31325-2-git-send-email-quic_c_skakit@quicinc.com


Signed-off-by: Mark Brown <broonie@kernel.org>