LU-5975 quota: remove obsolete quota code

LU-5975 quota: remove obsolete quota code

Remove the obsolete quotacheck, quotaon and quotaoff, which
were retained for the interoprability with old (< 2.4) client
and server.

Some other obsolete quota code related to LL_IOC_QUOTACTL_18,
Q_INVLIDATE and Q_FINVALIDATE are removed as well.

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: I21cd14d9fb783c1bfa09668b318189a24bf72224
Reviewed-on: http://review.whamcloud.com/14705
Tested-by: Jenkins
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>