ARM: dts: at91: sam9x60ek: Disable slewrate on QSPI pins

QSPI pins have switching frequency above 50Mhz, so slewrate must be
disabled.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>

Author: Codrin Ciubotariu

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

@@ -453,12 +453,12 @@
 				qspi {
 					pinctrl_qspi: qspi {
 						atmel,pins =
-							<AT91_PIOB 19 AT91_PERIPH_A AT91_PINCTRL_NONE
-							 AT91_PIOB 20 AT91_PERIPH_A AT91_PINCTRL_NONE
-							 AT91_PIOB 21 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
-							 AT91_PIOB 22 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
-							 AT91_PIOB 23 AT91_PERIPH_A AT91_PINCTRL_PULL_UP
-							 AT91_PIOB 24 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
+							<AT91_PIOB 19 AT91_PERIPH_A AT91_PINCTRL_SLEWRATE_DIS
+							 AT91_PIOB 20 AT91_PERIPH_A AT91_PINCTRL_SLEWRATE_DIS
+							 AT91_PIOB 21 AT91_PERIPH_A (AT91_PINCTRL_PULL_UP | AT91_PINCTRL_SLEWRATE_DIS)
+							 AT91_PIOB 22 AT91_PERIPH_A (AT91_PINCTRL_PULL_UP | AT91_PINCTRL_SLEWRATE_DIS)
+							 AT91_PIOB 23 AT91_PERIPH_A (AT91_PINCTRL_PULL_UP | AT91_PINCTRL_SLEWRATE_DIS)
+							 AT91_PIOB 24 AT91_PERIPH_A (AT91_PINCTRL_PULL_UP | AT91_PINCTRL_SLEWRATE_DIS)>;
 					};
 				};