rtc: pm8xxx: Add RTC support for PMIC PMK8350

Add the comaptible string for PMIC PMK8350.

Signed-off-by: satya priya <skakit@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1617976766-7852-2-git-send-email-skakit@codeaurora.org