bmcweb: add mutual-tls-auth PACAKGECONFIG

meta-ibm already overrides this meson setting in some cases.  Promote it
to a PACKAGECONFIG so it is clearer as to which machines have it enabled
and which have it disabled.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I198d2ac1f403317f0eaf4ee2a348da87707d8820
diff --git a/meta-ibm/recipes-phosphor/interfaces/bmcweb_%.bbappend b/meta-ibm/recipes-phosphor/interfaces/bmcweb_%.bbappend
index 40cb816..16ef554 100644
--- a/meta-ibm/recipes-phosphor/interfaces/bmcweb_%.bbappend
+++ b/meta-ibm/recipes-phosphor/interfaces/bmcweb_%.bbappend
@@ -8,16 +8,16 @@
 "
 
 EXTRA_OEMESON:append:p10bmc = " \
-    -Dmutual-tls-auth=disabled \
     -Dkvm=disabled \
     -Dvm-websocket=disabled \
 "
+PACKAGECONFIG:remove:p10bmc = "mutual-tls-auth"
 
 EXTRA_OEMESON:append:witherspoon-tacoma = " \
-    -Dmutual-tls-auth=disabled \
     -Dkvm=disabled \
     -Dvm-websocket=disabled \
 "
+PACKAGECONFIG:remove:witherspoon-tacoma = "mutual-tls-auth"
 
 EXTRA_OEMESON:append:system1 = " \
      -Dhttp-body-limit=400 \