ARM: mach-shmobile: mackerel: clarify shdi/mmcif switch settings

* Pins 2 and 4 of switch 33 are documented as don't care on the PCB,
  my testing seems to confirm this.

* I have been unable to do anything sensible with S1 set to on.
  Am I missing something with regards to MMC1?

* Clarify which driver is needed for each switch setting.

* Should the AP4 board code be updated to allow the
  SHDI driver to access SHDI1 as the mackerel code does?

Signed-off-by: Simon Horman <horms@verge.net.au>
Acked-by: Yusuke Goda <yusuke.goda.sx@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/arm/mach-shmobile/board-mackerel.c

@@ -169,9 +169,8 @@
  *	SW1	|	SW33
  *		| bit1 | bit2 | bit3 | bit4
  * -------------+------+------+------+-------
- * MMC0	  OFF	|  OFF |  ON  |  ON  |  X
- * MMC1	  ON	|  OFF |  ON  |  X   | ON
- * SDHI1  OFF	|  ON  |   X  |  OFF | ON
+ * MMC0   OFF	|  OFF |   X  |  ON  |  X       (Use MMCIF)
+ * SDHI1  OFF	|  ON  |   X  |  OFF |  X       (Use MFD_SH_MOBILE_SDHI)
  *
  */