ARM: dts: at91: sama7g5: fix signal name of pin PB2

The signal name of pin PB2 with function F is FLEXCOM11_IO1
as it is defined in the datasheet.

Fixes: 558378a4 ("ARM: mach-at91: add support for new SoC sama7g5")
Signed-off-by: Mihai Sain <mihai.sain@microchip.com>