ARM: dts: at91: sam9x60: fix mux-mask for PA7 so it can be set to A, B and C

According to the datasheet PA7 can be set to either function A, B or
C (see table 6-2 of DS60001579D). The previous value would permit just
configuring with function C.

Signed-off-by: Federico Pellegrin <fede@evolware.org>
Fixes: 1e5f532c27 ("ARM: dts: at91: sam9x60: add device tree for soc and board")
Cc: <stable@vger.kernel.org> # 5.6+
Cc: Sandeep Sheriker Mallikarjun <sandeepsheriker.mallikarjun@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>

arch/arm/boot/dts/at91-sam9x60ek.dts

@@ -336,7 +336,7 @@
 &pinctrl {
 	atmel,mux-mask = <
 			 /*	A	B	C	*/
-			 0xFFFFFE7F 0xC0E0397F 0xEF00019D	/* pioA */
+			 0xFFFFFEFF 0xC0E039FF 0xEF00019D	/* pioA */
 			 0x03FFFFFF 0x02FC7E68 0x00780000	/* pioB */
 			 0xffffffff 0xF83FFFFF 0xB800F3FC	/* pioC */
 			 0x003FFFFF 0x003F8000 0x00000000	/* pioD */