Fix 'swuupdate' typo in swupdate-image.bb

Signed-off-by: Christian Storm <christian.storm@siemens.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>

recipes-extended/images/swupdate-image.bb

@@ -1,4 +1,4 @@
-SUMMARY = "Root filesystem for swuupdate as rescue system"
+SUMMARY = "Root filesystem for swupdate as rescue system"
 DESCRIPTION = "Root FS to start swupdate in rescue mode	\
 		"