meta-phosphor: split image type configs to includes

We have reached branch-capacity in the bb.utils.contains checks
at 3 image types.  In order to be able to more easily add additional
image types, split the differences out into additional inc-snippets
for each image type.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ibcdb5c885c67cb6d8728dfd315eb07f99b1a2173
diff --git a/meta-phosphor/conf/machine/include/image-type/ubi-fs.inc b/meta-phosphor/conf/machine/include/image-type/ubi-fs.inc
new file mode 100644
index 0000000..62e66a6
--- /dev/null
+++ b/meta-phosphor/conf/machine/include/image-type/ubi-fs.inc
@@ -0,0 +1,2 @@
+IMAGE_FSTYPES += "mtd-ubi mtd-ubi-tar"
+INITRAMFS_IMAGE = ""