SDI0/SDI1 can be used in configurations where some of the pins
(e.g. direction control) are not used. The pinctrl driver has
separate pin groups for them.

Add new pin configurations for:
  - mc0_a_2: like mc0_a_1, but without CMDDIR/DAT0DIR/DAT2DIR
  - mc1_a_2: like mc1_a_1, but without FBCLK
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20191125122256.53482-3-stephan@gerhold.netSigned-off-by: Linus Walleij <linus.walleij@linaro.org>