x86/microcode/AMD: Get rid of the _load_microcode_amd() forward declaration

Simply move save_microcode_in_initrd() down.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20250211163648.30531-5-bp@kernel.org