ARM: dts: at91: sama5d4: fix pinctrl muxing

Fix pinctrl muxing, PD28, PD29 and PD31 can be muxed to peripheral A. It
allows to use SCK0, SCK1 and SPI0_NPCS2 signals.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Fixes: 679f8d92 ("ARM: at91/dt: sama5d4: add pioD pin mux mask and enable pioD")
Cc: stable@vger.kernel.org # v4.4+
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20191025084210.14726-1-ludovic.desroches@microchip.com