staging: lustre: quota: remove obsolete quota code

Remove the obsolete quotacheck, quotaon and quotaoff, which
were retained for the interoperability 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>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5975
Reviewed-on: http://review.whamcloud.com/14705


Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>