verity: don't pass hash_desc down the stack

Simplify the code by grabbing a hash_desc reference inside compute_hash().

BUG=9752
TEST=Ran platform_DMVerityCorruption on H/W.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
kernel.git Review URL: http://codereview.chromium.org/6660003

TBRing since code has already been review and LGTMed for kernel.git

Change-Id: Ia613b08fa4584cac2b26e948220a0a0a45058991

TBRR=wad@chromium.org,taysom@chromium.org,ups@chromium.org

Review URL: http://codereview.chromium.org/6705011
1 file changed