acpi_gpiobus: mask pin flags for GPIOBUS_PIN_SETFLAGS

GPIOBUS_PIN_SETFLAGS calls GPIO_PIN_SETFLAGS, which doesn't accept
interrupt flags.

Reviewed-by: Warner Losh <imp@FreeBSD.org>
Pull-request: https://github.com/freebsd/freebsd-src/pull/1667
Signed-off-by: Ahmad Khalifa <ahmadkhalifa570@gmail.com>