only release cmrt device when it is already created
only release cmrt device when it is already created

this patch fixed the issue at https://bugs.freedesktop.org/show_bug.cgi?id=95136

Signed-off-by: Guo Yejun <1f883e24fa2949df61a83c432caa290810cece11@intel.com>
Reviewed-by: Yang Rong <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>

wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet,wdv4758h/beignet