x86, mtrr: Remove unused mtrr/state.c

The last reference to the helpers in
<arch/x86/kernel/cpu/mtrr/state.c> went away with
9a6b344e leaving unused code.
Remove it.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20100204085128.GA513@liondog.tnic>
Signed-off-by: Ingo Molnar <mingo@elte.hu>