pinctrl: meson: axg: Fix GPIO pin offsets

The pin number (first and last) in the bank definition is missing the
pin base offset shifting. This is causing a miscalculation when
retrieving the register and pin offsets in the GPIO driver causing the
'gpio' command to drive the wrong pins / GPIOs in the second GPIO chip
(the AO bank is driven correctly because the shifting is already 0).

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>