x86/microcode: Use kmemdup() rather than duplicating its implementation

The patch was generated using fixed coccinelle semantic patch
scripts/coccinelle/api/memdup.cocci.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1455612202-14414-3-git-send-email-bp@alien8.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>