MLBEDSW-2379: Fix 1-element tensors that were marked as scalars

Tensors that are the result of an operation were incorrectly marked
as scalars.

Also fixes a bug for IFM2 of shape [*,*,*,1] in elementwise operations.

Signed-off-by: Louis Verhaard <louis.verhaard@arm.com>
Change-Id: I82a0e643b12e93c7158e4aca3185415c59033a73