Make board-h3.c file uses new board-h3-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_h3_1710_defconfig to use
  multislot support:
  - GPIO switch support
  - MSDOS fs support
  - VFAT fs support
  - Codepage 437
  - 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>