x86/microcode: Rip out the OLD_INTERFACE

[ Upstream commit 181b6f40 ]

Everything should be using the early initrd loading by now.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220525161232.14924-2-bp@alien8.de


Stable-dep-of: c0dd9245 ("x86/microcode: Check CPU capabilities after late microcode update correctly")
Signed-off-by: Sasha Levin <sashal@kernel.org>