gpio: max732x: use guard(mutex) to simplify locking

gpio: max732x: use guard(mutex) to simplify locking

Convert the max732x driver to use the RAII-based guard(mutex) macro from
<linux/cleanup.h>. This change replaces manual mutex_lock() and
mutex_unlock() calls, allowing the chip lock to be managed automatically
based on function scope.

Refactor max732x_gpio_set_mask() and max732x_irq_update_mask() to
improve code readability. This allows for direct returns and removes
the redundant 'out' label in the set_mask function, resulting in
cleaner and more maintainable code.

While at it: order includes alphabetically and add missing ones.

Signed-off-by: Richard Lyu <richard.lyu@suse.com>
Link: https://patch.msgid.link/20260311085924.191288-1-richard.lyu@suse.com
[Bartosz: tweak commit message, add err.h and device.h to includes]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>