sched: hmp: fix wrong initialization of hmp_data

sched: hmp: fix wrong initialization of hmp_data

There was wrong memset for hmp_data, so this patch fixes it. This also
fixes following build warning.

   kernel/sched/fair.c: In function 'hmp_attr_init':
   kernel/sched/fair.c:5642:2: warning: 'memset' used with constant zero length parameter; this could be due to transposed parameters [-Wmemset-transposed-args]
     memset(&hmp_data, sizeof(hmp_data), 0);
     ^

Change-Id: I2d1b49b2591015fab011a150278f6688324411f6
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>