fix amd mainboard configs

in a build test, canoeboot 0.1 builds, but master doesn't,
and neither does lbmk. i changed a few of them when doing
the crossgcc build optimisation patches.

i'm just copying the configs from there. unlike in the
canoeboot version of this patch, i've re-enabled microcode
updates in these lbmk configs.

Signed-off-by: Leah Rowe <leah@libreboot.org>

config/coreboot/fam15h_rdimm/target.cfg

@@ -1,7 +1,2 @@
 tree="fam15h_rdimm"
 rev="1c13f8d85c7306213cd525308ee8973e5663a3f8"
-payload_grub="n"
-payload_grub_withseabios="n"
-payload_seabios="n"
-payload_memtest="n"
-xlang="c"