mon/OSDMonitor: reject updating upmap if number of osd overflows/underflows

mon/OSDMonitor: reject updating upmap if number of osd overflows/underflows

This can avoid, e.g.:

~#:./bin/ceph osd pg-upmap 0.7 1 2 3 4
set 0.7 pg_upmap mapping to [1,2,3,4]

~#:./bin/ceph pg dump
PG_STAT OBJECTS MISSING_ON_PRIMARY DEGRADED MISPLACED UNFOUND BYTES LOG DISK_LOG STATE        STATE_STAMP                VERSION REPORTED UP        UP_PRIMARY ACTING    ACTING_PRIMARY LAST_SCRUB SCRUB_STAMP                LAST_DEEP_SCRUB DEEP_SCRUB_STAMP
0.7           0                  0        0         0       0     0   0        0      peering 2017-06-24 10:11:03.938102     0'0    53:18 [1,2,3,4]          1 [1,2,3,4]              1        0'0 2017-06-24 09:38:50.162197             0'0 2017-06-24 09:38:50.162197

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>