MMC: OMAP: Make board-h2.c uses new board-h2-mmc.c code

Make board-h2.c file uses new board-h2-mmc.c code.

This patch also:
- Introduces a new gpio_switch to get events when inserting and removing
  MMC/SD/SDIO cards to/from the slot.
- Enables the following options on omap_h2_1610_defconfig to use
  multislot support:
  - GPIO switch support
  - MMC/SD card support
  - VFAT fs support
  - NLS ISO 8859-1

Signed-off-by: Felipe Balbi <felipe.lima@indt.org.br>
Signed-off-by: Anderson Briglia <anderson.briglia@indt.org.br>
Signed-off-by: Carlos Eduardo Aguiar <carlos.aguiar@indt.org.br>
Signed-off-by: David Cohen <david.cohen@indt.org.br>
Signed-off-by: Eduardo Valentin <eduardo.valentin@indt.org.br>
Signed-off-by: Tony Lindgren <tony@atomide.com>