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>