pldm: Add oem-ibm build option

Currently, several machines use the oem-ibm function in the
pldm_%.bbappend file. It should be added to PACKAGECONFIG in the
pldm_git recipe and disabled by default.

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: Ia120de9ad80f24333575e3b278ff14c3272a4733
diff --git a/meta-ibm/recipes-phosphor/pldm/pldm_%.bbappend b/meta-ibm/recipes-phosphor/pldm/pldm_%.bbappend
index d997e16..589bf3d 100644
--- a/meta-ibm/recipes-phosphor/pldm/pldm_%.bbappend
+++ b/meta-ibm/recipes-phosphor/pldm/pldm_%.bbappend
@@ -1,8 +1,5 @@
 # Force the mctp-demux to be used until machine is ready to use in-kernel MCTP
-PACKAGECONFIG = "transport-mctp-demux"
-
-PACKAGECONFIG += "oem-ibm"
-PACKAGECONFIG[oem-ibm] = "-Doem-ibm=enabled, -Doem-ibm=disabled, , squashfs-tools"
+PACKAGECONFIG:append = " transport-mctp-demux oem-ibm"
 
 EXTRA_OEMESON += " \
         -Dsoftoff-timeout-seconds=2700 \