x86/microcode/AMD: Rename a couple of functions

- Rename apply_microcode_early_amd() to early_apply_microcode():
simplify the name so that it is clear what it does and when does it do
it.

- Rename __load_ucode_amd() to find_blobs_in_containers(): the new name
actually explains what it does.

Document some.

No functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20221219210656.5140-1-bp@alien8.de