ARM: dts: at91: sama5d2_xplained: remove PA11__SDMMC0_VDDSEL from pinctrl

I/O voltage for eMMC is always 3.3V because PA11__SDMMC0_VDDSEL is
tied with 10K resistor to GND. U13 switch S1 is always selected as
voltage rail of 3.3V for VCCQ power pin from MPU controller and eMMC flash.
Removing PA11 from pinctrl because it remains unused.

Signed-off-by: Mihai Sain <mihai.sain@microchip.com>
Reviewed-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20211026132034.678655-1-eugen.hristev@microchip.com