x86/microcode: Remove local vendor variable

Use x86_cpuid_vendor() directly.

No functionality change.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20170120202955.4091-12-bp@alien8.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>