x86/CPU/AMD: Get rid of amd_erratum_400[]

Setting X86_BUG_AMD_E400 in init_amd() is early enough.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: http://lore.kernel.org/r/20231120104152.13740-12-bp@alien8.de