x86/microcode/intel: Simplify and rename generic_load_microcode()

so it becomes less obfuscated and rename it because there is nothing
generic about it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231002115902.330295409@linutronix.de