hammerhead: Better mount options to improve performance

Change-Id: I18f7165c2ff8547b7968d946336d948fe30522b1
Revert "HACK: Disable secure discard"

This reverts commit 499335d644d72560f72a3ed912434deb0322c4f3.

Change-Id: I092be33a22bfeb55b0a0ffbcbd3a3bf896700b58
hammerhead: enable BOARD_SUPPRESS_SECURE_ERASE

 * with this enabled it greatly reduces formatting times

Change-Id: I58db88456ebb39a83923ba5c167434298bf85760