This reverts commit f0b0e4bec1e89014f3dcef4da8bcf95428cc771c.
The reverted commit incorrectly calculates the size of eMMC
devices in some (all?) cases.
This revert may cause problems in cases where the bootloader was
bug-compatible and puts a GPT partition at the incorrect end of
the eMMC device.
Signed-off-by: Colin Cross <ccross@android.com>