x86/microcode/intel: Use *wrmsrl variants

... and drop the 32-bit casting games which we had to do at the time
because wrmsr() was unforgiving then, see c3fd0bd5e19a from the
full history tree:

  commit c3fd0bd5e19aaff9cdd104edff136a2023db657e
  Author: Linus Torvalds <torvalds@home.osdl.org>
  Date:   Tue Feb 17 23:23:41 2004 -0800

    Fix up the microcode update on regular 32-bit x86. Our wrmsr()
    is a bit unforgiving and really doesn't like 64-bit values.
    ...

Tested-by: Thomas Voegtle <tv@lio96.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1454499225-21544-13-git-send-email-bp@alien8.de


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