i965: support UYVY for external import only

It is similar with YUYV

Fixes: 165e7047 ("i965/i915: Add UYVY as the supported format")
Signed-off-by: Haihao Xiang <haihao.xiang@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
(cherry picked from commit 8ead5beb)