ARM: dts: microchip: sam9x7: fix gpio-lines count for pioB

ARM: dts: microchip: sam9x7: fix gpio-lines count for pioB

The pioB controller on the SAM9X7 SoC actually supports 27 GPIO lines.
The previous value of 26 was incorrect, leading to the last pin being
unavailable for use by the GPIO subsystem.
Update the #gpio-lines property to reflect
the correct hardware specification.

Fixes: 41af45af8bc3 ("ARM: dts: at91: sam9x7: add device tree for SoC")
Signed-off-by: Mihai Sain <mihai.sain@microchip.com>
Link: https://lore.kernel.org/r/20260209090735.2016-1-mihai.sain@microchip.com
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>