MLBEDSW-10631: Modify CONST error check

CONST operator error check assumed exact size match between buffer and
OFM tensor storage size bytes. That failed since TOSA tensors are 8 byte
aligned. Changed to check that buffer has enough elements to fill OFM
instead.

Change-Id: Ice7ddc04707d81e27f5f26317ab12fe5640008d9
Signed-off-by: Rickard Bolin <rickard.bolin@arm.com>