Patch a4817a6b added the sub8x8tx_in_gte8x8blk_in_plane0 variable, but
it's read in a block that doesn't exist if DISABLE_TRELLISQ_SEARCH is
true, causing a warning in the overnight "lv-map" unit tests.

Change-Id: I916b61957ffdad1ac7be38efd4051d266d4bd61c