verity: change maybe_read_entries to maybe_read_entry

Since root is guaranteed to be a single block we no longer need to
read multiple entries in maybe_read_entries.

BUG=9752
TEST=Ran dm-verity.git unit tests. Ran platform_DMVerityCorruption on H/W.

kernel-next.git Review URL: http://codereview.chromium.org/6821076

TBRing. Already LGTMed and committed to kernel-next.git

Change-Id: I23e19d13e7f3b079a5fe739be7fdd9f2df760335

R=wad@chromium.org,taysom@chromium.org

Review URL: http://codereview.chromium.org/6880133
1 file changed