x86: asm-x86/msr.h: pull in linux/types.h

Since the msr.h header uses types like __u32, it should pull in linux/types.h.

[ mingo@elte.hu: affects user-space that includes this header. We dont
  actually like user-space including raw kernel headers but it's a
  longstanding practice and it's easy for the kernel to be nice about
  this. ]

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>