[ARM] ecard: add helper function for setting ecard irq ops

Rather than having every driver fiddle about setting its private
IRQ operations and data, provide a helper function to contain
this functionality in one place.

Arrange to remove the driver-private IRQ operations and data when
the device is removed from the driver, and remove the driver
private code to do this.

This fixes potential problems caused by drivers forgetting to
remove these hooks.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>