v4l2-ctl: add support for custom bytesperline values.

v4l2-ctl: add support for custom bytesperline values.

The V4L2 API allows application to select a bytesperline value that's larger
than what the driver gives you, effectively padding each line.

Add support to v4l2-ctl to set custom bytesperline values when trying/setting
new formats.

This also fixes a bug where setting multiplanar formats failed: in the *_cmd
function the is_multiplanar global variable isn't set yet because the device
hasn't been opened. So it always assumed a single planar format.

The fixed code is actually cleaner than what I had before.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>