pinctrl: stmfx: Fix 'warn: bitwise AND condition is false here'

drivers/pinctrl/pinctrl-stmfx.c:441 stmfx_pinctrl_irq_set_type() warn: bitwise AND condition is false here

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>