regulator: pca9450: Correct interrupt type

regulator: pca9450: Correct interrupt type

Kernel warning on i.MX8MP-EVK when doing module test:
irq: type mismatch, failed to map hwirq-3 for gpio@30200000!

Per PCA945[X] specification: The IRQ_B pin is pulled low when any unmasked
interrupt bit status is changed and it is released high once application
processor read INT1 register.

So the interrupt should be configured as IRQF_TRIGGER_LOW, not
IRQF_TRIGGER_FALLING.

Fixes: 0935ff5f1f0a4 ("regulator: pca9450: add pca9450 pmic driver")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://patch.msgid.link/20260310-pca9450-irq-v1-1-36adf52c2c55@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>