Convert obmc-ubi-fs to a distro feature

As with MRW the use of the UBI image scheme is distro policy.
Convert the existing machine feature to a distro feature.

Enable the new distro feature on the systems that use
it(Witherspoon).

Add a distro override and fix-up MF checks to use this override
instead for improved readability.

Tested: Built a Witherspoon image and validated image
Change-Id: I8ab03115bbfc2ecc77cff5c9eb8628903ae88051
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc b/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc
index 983c33f..e1eb738 100644
--- a/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc
+++ b/meta-phosphor/common/recipes-bsp/u-boot/u-boot-aspeed.inc
@@ -2,17 +2,17 @@
 
 SRC_URI_append_aspeed = " file://0001-configs-ast-Add-redundnant-env.patch"
 
-SRC_URI_append_aspeed = " ${@bb.utils.contains('MACHINE_FEATURES', 'obmc-ubi-fs', \
-    'file://0002-config-ast-common-hack-bootopts.patch \
-     file://0003-config-ast-common-Add-bootopts-to-support-ubi-and-mt.patch \
-     file://0004-config-ast-common-Add-conditional-factory-reset-comm.patch', '', d)}"
+SRC_URI_append_aspeed_df-obmc-ubi-fs = " \
+    file://0002-config-ast-common-hack-bootopts.patch \
+    file://0003-config-ast-common-Add-bootopts-to-support-ubi-and-mt.patch \
+    file://0004-config-ast-common-Add-conditional-factory-reset-comm.patch \
+    "
 
 
-python do_configure_aspeed () {
-    if "obmc-ubi-fs" in d.getVar("MACHINE_FEATURES", True):
-        version_id=do_get_versionID(d)
-        d.setVar('VERSION_ID', version_id)
-        bb.build.exec_func("patch_uboot", d)
+python do_configure_aspeed_df-obmc-ubi-fs () {
+    version_id=do_get_versionID(d)
+    d.setVar('VERSION_ID', version_id)
+    bb.build.exec_func("patch_uboot", d)
 }
 
 patch_uboot () {