board/pine64/rockpro64/genimage.cfg: beautify file

Beatify this genimage .cfg file to have consistency with all genimage .cfg
files in Buildroot.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

board/pine64/rockpro64/genimage.cfg

@@ -6,11 +6,11 @@ image boot.vfat {
 			"extlinux"
 		}
 	}
+
 	size = 64M
 }
 
 image sdcard.img {
-
 	hdimage {
 		gpt = true
 	}