posix-timers: Remove mmtimer leftovers

After removing mmtimer, the mmtimer struct can be removed from the k_itimer
struct.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Russ Anderson <rja@sgi.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20170526130534.GE30788@hpe.com

include/linux/posix-timers.h

@@ -72,12 +72,6 @@ struct k_itimer {
 			ktime_t interval;
 		} real;
 		struct cpu_timer_list cpu;
-		struct {
-			unsigned int clock;
-			unsigned int node;
-			unsigned long incr;
-			unsigned long expires;
-		} mmtimer;
 		struct {
 			struct alarm alarmtimer;
 			ktime_t interval;