openpower: Run firmware whitelist for all machines

Firenze has a script that ensures only the correct firmware is present
in the lib/firmware directory of skiroot. This is useful functionality
for all machines, so rename it and add it to the
ROOTFS_POST_BUILD_SCRIPT config option for all machines.

Note that this means adding new drivers that have loadable firwmare in
the future will require updating this script.

Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/openpower/configs/openpower_p9_mambo_defconfig b/openpower/configs/openpower_p9_mambo_defconfig
index 5624845..1e540a7 100644
--- a/openpower/configs/openpower_p9_mambo_defconfig
+++ b/openpower/configs/openpower_p9_mambo_defconfig
@@ -11,7 +11,7 @@
 BR2_TARGET_GENERIC_GETTY_PORT="hvc0"
 BR2_GENERATE_LOCALE="en_US.UTF-8"
 BR2_ROOTFS_OVERLAY="../openpower/overlay"
-BR2_ROOTFS_POST_BUILD_SCRIPT="../openpower/scripts/fixup-target-var"
+BR2_ROOTFS_POST_BUILD_SCRIPT="../openpower/scripts/fixup-target-var ../openpower/scripts/firmware-whitelist"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.8"