regulator: pf9453: Allow shared IRQ

regulator: pf9453: Allow shared IRQ

The PF9453 datasheet specifies the IRQ_B pin as an open drain output
with level-low behavior. This makes it capable to share the interrupt
line. To allow shared interrupts, the driver must handle the case
if the interrupt has been triggered by another device.

Set IRQF_SHARED to be able to share the interrupt line.
If the interrupt has not been triggered by the PMIC, return IRQ_NONE.

Signed-off-by: Franz Schnyder <franz.schnyder@toradex.com>
Link: https://patch.msgid.link/20260302165357.1797803-3-fra.schnyder@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>