Driver for the external-charger IRQ pass-through function of the
Intel Bay Trail Crystal Cove PMIC.

Note this is NOT a power_supply class driver, it just deals with IRQ
pass-through, this requires this separate driver because the PMIC's
level 2 interrupt for this must be explicitly acked.

This new driver gets enabled by the existing X86_ANDROID_TABLETS Kconfig
option because the x86-android-tablets module is the only consumer of the
exported external-charger IRQ.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20211225115509.94891-5-hdegoede@redhat.com