pinctrl: intel: Show the GPIO base calculation explicitly

During the split of intel_pinctrl_add_padgroups(), the _by_size() variant
missed the GPIO base calculations and hence made unable to retrieve proper
GPIO number.

Assign the gpio_base explicitly in _by_size() variant.

While at it, differentiate NOMAP case with the rest in _by_gpps() variant.

Fixes: 036e126c ("pinctrl: intel: Split intel_pinctrl_add_padgroups() for better maintenance")
Reported-and-tested-by: Maximilian Luz <luzmaximilian@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>