evita: 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_USES_MMCUTIL: cannot find source that utilizes this

Change-Id: Ib4c2f1f7826252e74fb9006533442b46c33cf589