meta-openpower: fix file search paths

Typically it does not make any sense to append to FILESEXTRAPATHS.
FILESEXTRAPATHS is set in a bbappend when overriding something from
another layer.  The typical desire will be to make bitbake search for
files in the layer with the bbappend and not some other layer earlier in
the priority list.  Further, appending to FILESEXTRAPATHS will introduce
unexpected behavior when multiple layers append the same recipe - layers
with higher layer priorities that append to FILESEXTRAPATHS will find
their files overriden by files in layers with lower priorities.

(From meta-openpower rev: 6e889e3889a474e481dc78890696b922a3bbbafc)

Change-Id: I3607828dea6bd16b457ce3de3a26320ac8525f66
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-openpower/recipes-bsp/skiboot/skiboot.inc b/meta-openpower/recipes-bsp/skiboot/skiboot.inc
index ab455b0..51d089e 100644
--- a/meta-openpower/recipes-bsp/skiboot/skiboot.inc
+++ b/meta-openpower/recipes-bsp/skiboot/skiboot.inc
@@ -4,7 +4,7 @@
 SRC_URI += "git://github.com/open-power/skiboot.git"
 SRC_URI += "file://0001-libffs-fix-gcc8-stringop-truncation-warnings.patch"
 
-FILESEXTRAPATHS_append := "${THISDIR}/skiboot:"
+FILESEXTRAPATHS_prepend := "${THISDIR}/skiboot:"
 
 LIC_FILES_CHKSUM = "file://${S}/LICENCE;md5=3b83ef96387f14655fc854ddc3c6bd57"
 
diff --git a/meta-openpower/recipes-phosphor/flash/phosphor-software-manager_%.bbappend b/meta-openpower/recipes-phosphor/flash/phosphor-software-manager_%.bbappend
index e873e99..4f2ea98 100644
--- a/meta-openpower/recipes-phosphor/flash/phosphor-software-manager_%.bbappend
+++ b/meta-openpower/recipes-phosphor/flash/phosphor-software-manager_%.bbappend
@@ -1,4 +1,4 @@
-FILESEXTRAPATHS_append_df-openpower := "${THISDIR}/${PN}:"
+FILESEXTRAPATHS_prepend_df-openpower := "${THISDIR}/${PN}:"
 
 SYSTEMD_OVERRIDE_${PN}-updater_append_df-openpower = \
     " software-bmc-updater.conf:xyz.openbmc_project.Software.BMC.Updater.service.d/software-bmc-updater.conf"