gpio: pca953x: Fix AI overflow on PCAL6524

The PCAL_PINCTRL_MASK is too large. The extended register block on
PCAL6524, which is the largest chip with this block, has the block
limited to address range 0x40..0x7f. This is because the bit 7 in
the command register is used for the Address Increment functionality.

Trim the mask to 0x60 to match the datasheet and to prevent accidental
overwrite of the AI bit.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>