Bluetooth: btnxpuart: Uses threaded IRQ for host wakeup handling

Bluetooth: btnxpuart: Uses threaded IRQ for host wakeup handling

This replaces devm_request_irq() with devm_request_threaded_irq().

On iMX93 11x11 EVK platform, the BT chip's BT_WAKE_OUT pin is connected
to an I2C GPIO expander instead of directly been connected to iMX GPIO.

When I2C GPIO expander's (PCAL6524) host driver receives an interrupt on
it's INTR line, the driver's interrupt handler needs to query the
interrupt source with PCAL6524 first, and then call the actual interrupt
handler, in this case the IRQ handler in BTNXPUART.

In order to handle interrupts when such I2C GPIO expanders are between
the host and interrupt source, devm_request_threaded_irq() is needed.

This commit also removes the IRQF_TRIGGER_FALLING flag, to allow setting
the IRQ trigger type from the device tree setting instead of hardcoding
in the driver.

Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Reviewed-by: Sherry Sun <sherry.sun@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>