package/swupdate: add missing backslash

Commit 0b4a9930124f7fb4c7bfae281db900905006a2da ("package/swupdate:
specify SWU_VER during build") forgot a backslash.

Fixes the following check-package warning:

package/swupdate/swupdate.mk:213: unexpected indent with tabs

and obviously makes the code correct.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
1 file changed