board/minnowboard/genimage.cfg: fix option assignment spaces

Option 'size=10M' must be 'size = 10M'.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/minnowboard/genimage.cfg

@@ -9,7 +9,7 @@ image efi-part.vfat {
 		}
 	}
 
-	size=10M
+	size = 10M
 }
 
 # Create the sdcard image, pulling in