x86/microcode: Parse built-in microcode early

Apparently, people do build microcode into the kernel image, i.e.
CONFIG_FIRMWARE_IN_KERNEL=y.

Make that work in the early loader which is where microcode should be
preferably loaded anyway.

Note that you need to specify the microcode filename with the path
relative to the toplevel firmware directory (the same like the late
loading method) in CONFIG_EXTRA_FIRMWARE=y so that early loader can
find it.

I.e., something like this (Intel variant):

  CONFIG_FIRMWARE_IN_KERNEL=y
  CONFIG_EXTRA_FIRMWARE="intel-ucode/06-3a-09"
  CONFIG_EXTRA_FIRMWARE_DIR="/lib/firmware/"

While at it, add me to the loader copyright boilerplate.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel J Blueman <daniel@numascale.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>