x86: first step of refactoring, introducing microcode_ops

x86: first step of refactoring, introducing microcode_ops

Refactoring with the goal of having one general module and separate
vendor specific modules that hook into the general one.

Microcode_ops is a function pointer structure in which vendor
specific modules will enter all functions that differ between
vendors and that need to be accessed from the general module.

Signed-off-by: Peter Oruba <peter.oruba@amd.com>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>