meta-ibm: witherspoon: add symlink for phosphor-network

Add a symlink name phosphor-network_%.bbappend that points to the
network_%.bbappend file.  This change will allow the recipe
phosphor-network_git.bb to start being used.  Once that's in place, the
network_%.bbappend file will become phosphor-network_%.bbappend.

Tested: Verified the witherspoon image built, but did not test further.
Change-Id: I9569f7fd6b118ce70f30037a9a2297f2104f6159
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/meta-witherspoon/recipes-phosphor/network/phosphor-network_%.bbappend b/meta-witherspoon/recipes-phosphor/network/phosphor-network_%.bbappend
new file mode 120000
index 0000000..75338c0
--- /dev/null
+++ b/meta-witherspoon/recipes-phosphor/network/phosphor-network_%.bbappend
@@ -0,0 +1 @@
+network_%.bbappend
\ No newline at end of file