ARM: dts: imx6sl-evk: Add an entry for MX6SL_PAD_ECSPI1_SS0__GPIO4_IO11

In case the bootloader has incorrectly configured the ALT mode of
MX6SL_PAD_ECSPI1_SS0 pad, we end up with the following probe error:

m25p80 spi0.0: found mr25h256, expected m25p32
m25p80 spi0.0: mr25h256 (32 Kbytes)

In order to avoid this issue, add an entry for MX6SL_PAD_ECSPI1_SS0 pad, so
that kernel configures the ECSPI chip select as GPIO functionality, which
results in correct SPI NOR probe.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>

arch/arm/boot/dts/imx6sl-evk.dts

@@ -282,6 +282,7 @@ pinctrl_ecspi1: ecspi1grp {
 				MX6SL_PAD_ECSPI1_MISO__ECSPI1_MISO	0x100b1
 				MX6SL_PAD_ECSPI1_MOSI__ECSPI1_MOSI	0x100b1
 				MX6SL_PAD_ECSPI1_SCLK__ECSPI1_SCLK	0x100b1
+				MX6SL_PAD_ECSPI1_SS0__GPIO4_IO11	0x80000000
 			>;
 		};