kernel-fitimage: fix missing TEE extension, as not provided by OPTEEFLAVOR
kernel-fitimage: fix missing TEE extension, as not provided by OPTEEFLAVOR

In the past, FITIMAGE_TEE listed TEE files with extension, but currently used
OPTEEFLAVOR variable only provides the name w/o extension.

Signed-off-by: Denys Dmytriyenko <d29de71aea38aad3a87d486929cb0aad173ae612@ti.com>

rcn-ee/meta-arago,rcn-ee/meta-arago,rcn-ee/meta-arago,rcn-ee/meta-arago,rcn-ee/meta-arago