media: vimc: cap: fix step width/height in enum framesize

The type V4L2_FRMSIZE_TYPE_CONTINUOUS expects a step of 1.
This fixes v4l2-compliance test error:

        fail: v4l2-test-formats.cpp(184): invalid step_width/height for continuous framesize
test VIDIOC_ENUM_FMT/FRAMESIZES/FRAMEINTERVALS: FAIL

Signed-off-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>