cpumask: Use modern cpumask style in arch/x86/kernel/cpu/mcheck/mce-inject.c

Note that there's no freeing the cpu var, since this module has
no unload function.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
LKML-Reference: <200911031458.30987.rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>