Recovery: remove unnecessary BoardConfig parameters

BOARD_SUPPRESS_EMMC_WIPE: according to http://review.cyanogenmod.org/17326 ,
this is only relevant to Samsung devices with buggy firmware

BOARD_VOLD_EMMC_SHARES_DEV_MAJOR: already defined in the # Vold section

BOARD_USES_MMCUTIL: cannot find source that utilizes this

Change-Id: I3bc5417e27bbd326b36f63be6384a24b25b70a5b