S390: BIOS create link to src folder for .img file

For *.img files, there will be a link created directly to the src folder,
like for all other blobs.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

configure

@@ -4518,6 +4518,7 @@ for bios_file in \
     $source_path/pc-bios/*.aml \
     $source_path/pc-bios/*.rom \
     $source_path/pc-bios/*.dtb \
+    $source_path/pc-bios/*.img \
     $source_path/pc-bios/openbios-* \
     $source_path/pc-bios/palcode-*
 do