Change RESIZE border attribute to int16_t

The restriction on border limits in the ERROR_IF is
-16 * scale_y_n <= border_y < scale_y_n
and
scale_y_n <= (1 << 11)

Together, these imply

-(1 << 15) < border_y < (1 << 11)

which fits in 16 bits

Signed-off-by: Eric Kunze <eric.kunze@arm.com>
Change-Id: I843f29a5efd8ea3fe559d83d33a3280b39bc7068