fix(fiptool): avoid packing the zero size images in the FIP

Updated the fiptool to avoid packing the zero size images in
the FIP.
Also, updated the commitlint-json file to cover the fiptool
changes under a separate scope.

Change-Id: Id7ac3dcff0c7318546e49308d0f17b6cbd5eb24b
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>

.cz.json

@@ -809,6 +809,10 @@
                 {
                     "title": "STM32 Image",
                     "scopes": ["stm32image", "tools/stm32image"]
+                },
+                {
+                    "title": "fiptool",
+                    "scopes": ["fiptool"]
                 }
             ]
         },

tools/fiptool/fiptool.c

@@ -537,7 +537,7 @@ static int pack_images(const char *filename, uint64_t toc_flags, unsigned long a
 	for (desc = image_desc_head; desc != NULL; desc = desc->next) {
 		image_t *image = desc->image;
 
-		if (image == NULL)
+		if (image == NULL || (image->toc_e.size == 0ULL))
 			continue;
 		payload_size += image->toc_e.size;
 		entry_offset = (entry_offset + align - 1) & ~(align - 1);