software-manager: Favor ALLOW_EMPTY

A number of recipes remove PN from the package list.  While this
seems to work it is unconventional and puts us into dusty corners
of oe-core/bitbake.

Adopt a more conventional approach with ALLOW_EMPTY_${PN} = "1".

Change-Id: If19c9cf985878dc42f17a85f6762bbe20ffe5ee1
Tested: Built phosphor-software-manager and validated package contents
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb b/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb
index 3cd0756..bbbb866 100644
--- a/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb
+++ b/meta-phosphor/common/recipes-phosphor/flash/phosphor-software-manager.bb
@@ -13,10 +13,8 @@
     ${PN}-updater \
     ${PN}-sync \
 "
-PACKAGES =+ "${SOFTWARE_MGR_PACKAGES}"
-PACKAGES_remove = "${PN}"
-RDEPENDS_${PN}-dev = "${SOFTWARE_MGR_PACKAGES}"
-RDEPENDS_${PN}-staticdev = "${SOFTWARE_MGR_PACKAGES}"
+PACKAGE_BEFORE_PN += "${SOFTWARE_MGR_PACKAGES}"
+ALLOW_EMPTY_${PN} = "1"
 
 DBUS_PACKAGES = "${SOFTWARE_MGR_PACKAGES}"