ARM: dts: am335x-sl50: Fix cannot claim requested pins for spi0

We don't need to bitbang these pins anymore, instead we muxed these
pins as SPI, after this change, done in commit 6c69f726, we introduced
the following error:

 pinctrl-single 44e10800.pinmux: pin PIN85 already requested \
 by 44e10800.pinmux; cannot claim for 48030000.spi
 pinctrl-single 44e10800.pinmux: pin-85 (48030000.spi) status -22

Fixes: 6c69f726 ("ARM: dts: am335x-sl50: Enable SPI0 interface and Flash Memory")
Cc: <stable@vger.kernel.org> # 4.11
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am335x-sl50.dts

@@ -280,10 +280,6 @@ AM33XX_IOPAD(0x830, PIN_INPUT_PULLUP | MUX_MODE7)	/* nKbdInt - gpmc_ad12.gpio1_1
 			AM33XX_IOPAD(0x834, PIN_INPUT_PULLUP | MUX_MODE7)	/* nKbdReset - gpmc_ad13.gpio1_13 */
 			AM33XX_IOPAD(0x838, PIN_INPUT_PULLUP | MUX_MODE7)	/* nDispReset - gpmc_ad14.gpio1_14 */
 			AM33XX_IOPAD(0x844, PIN_INPUT_PULLUP | MUX_MODE7)	/* USB1_enPower - gpmc_a1.gpio1_17 */
-			/* AVR Programming - SPI Bus (bit bang) - Screen and Keyboard */
-			AM33XX_IOPAD(0x954, PIN_INPUT_PULLUP | MUX_MODE7)	/* Kbd/Disp/BattMOSI spi0_d0.gpio0_3 */
-			AM33XX_IOPAD(0x958, PIN_INPUT_PULLUP | MUX_MODE7)	/* Kbd/Disp/BattMISO spi0_d1.gpio0_4 */
-			AM33XX_IOPAD(0x950, PIN_INPUT_PULLUP | MUX_MODE7)	/* Kbd/Disp/BattSCLK spi0_clk.gpio0_2 */
 			/* PDI Bus - Battery system */
 			AM33XX_IOPAD(0x840, PIN_INPUT_PULLUP | MUX_MODE7)	/* nBattReset  gpmc_a0.gpio1_16 */
 			AM33XX_IOPAD(0x83c, PIN_INPUT_PULLUP | MUX_MODE7)	/* BattPDIData gpmc_ad15.gpio1_15 */