Add `CONFIG_CPU_MICROCODE_CBFS_NONE=y` to KGPE-D16 Coreboot configs. This disables microcode being included and loaded by Coreboot because of a current issue in which newer kernels panic when doing so.
Added note to KGPE-D16 configs about the current microcode bug, why microcode is not included and encouraging AMD Opteron 6300 series users to make sure their operating system loads microcode.