media: sti: hva: Remove useless check

Remove index range test since it is done by vb2_get_buffer().
vb2_get_buffer() can return a NULL pointer so we need the return
value.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
CC: Jean-Christophe Trotin <jean-christophe.trotin@foss.st.com>
Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>