selftests: netdevsim: use suitable existing dummy file for flash test

The file name used in flash test was "dummy" because at the time test
was written, drivers were responsible for file request and as netdevsim
didn't do that, name was unused. However, the file load request is
now done in devlink code and therefore the file has to exist.
Use first random file from /lib/firmware for this purpose.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/netdevsim/devlink.sh

@@ -31,36 +31,43 @@ devlink_wait()
 
 fw_flash_test()
 {
+	DUMMYFILE=$(find /lib/firmware -maxdepth 1 -type f  -printf '%f\n' |head -1)
 	RET=0
 
-	devlink dev flash $DL_HANDLE file dummy
+	if [ -z "$DUMMYFILE" ]
+	then
+		echo "SKIP: unable to find suitable dummy firmware file"
+		return
+	fi
+
+	devlink dev flash $DL_HANDLE file $DUMMYFILE
 	check_err $? "Failed to flash with status updates on"
 
-	devlink dev flash $DL_HANDLE file dummy component fw.mgmt
+	devlink dev flash $DL_HANDLE file $DUMMYFILE component fw.mgmt
 	check_err $? "Failed to flash with component attribute"
 
-	devlink dev flash $DL_HANDLE file dummy overwrite settings
+	devlink dev flash $DL_HANDLE file $DUMMYFILE overwrite settings
 	check_fail $? "Flash with overwrite settings should be rejected"
 
 	echo "1"> $DEBUGFS_DIR/fw_update_overwrite_mask
 	check_err $? "Failed to change allowed overwrite mask"
 
-	devlink dev flash $DL_HANDLE file dummy overwrite settings
+	devlink dev flash $DL_HANDLE file $DUMMYFILE overwrite settings
 	check_err $? "Failed to flash with settings overwrite enabled"
 
-	devlink dev flash $DL_HANDLE file dummy overwrite identifiers
+	devlink dev flash $DL_HANDLE file $DUMMYFILE overwrite identifiers
 	check_fail $? "Flash with overwrite settings should be identifiers"
 
 	echo "3"> $DEBUGFS_DIR/fw_update_overwrite_mask
 	check_err $? "Failed to change allowed overwrite mask"
 
-	devlink dev flash $DL_HANDLE file dummy overwrite identifiers overwrite settings
+	devlink dev flash $DL_HANDLE file $DUMMYFILE overwrite identifiers overwrite settings
 	check_err $? "Failed to flash with settings and identifiers overwrite enabled"
 
 	echo "n"> $DEBUGFS_DIR/fw_update_status
 	check_err $? "Failed to disable status updates"
 
-	devlink dev flash $DL_HANDLE file dummy
+	devlink dev flash $DL_HANDLE file $DUMMYFILE
 	check_err $? "Failed to flash with status updates off"
 
 	log_test "fw flash test"