pinctrl: st: Fix irqmux handler

pinctrl: st: Fix irqmux handler

commit 7a2deccf0ef12f7f6e33150d5875020c0c94fa94 upstream.

st_gpio_irqmux_handler() reads the status register to find out
which banks inside the controller have pending IRQs.
For each banks having pending IRQs, it calls the corresponding handler.

Problem is that current code restricts the number of possible banks inside the
controller to ST_GPIO_PINS_PER_BANK. This define represents the number of pins
inside a bank, so it shouldn't be used here.

On STiH407, PIO_FRONT0 controller has 10 banks, so IRQs pending in the two
last banks (PIO18 & PIO19) aren't handled.

This patch replace ST_GPIO_PINS_PER_BANK by the number of banks inside the
controller.

Cc: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>