drm/xe/bb: assert width in xe_bb_create_job()

The queue width will determine the number of batch buffer emitted into
the ring. In the case of xe_bb_create_job() we pass exactly one batch
address, therefore add an assert for the width to make sure we don't go
out of bounds. While here also convert to the helper to determine if the
queue is migration based.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240320112730.219854-3-matthew.auld@intel.com