LU-8066 osc: fix idle_timeout handling

LU-8066 osc: fix idle_timeout handling

The patch that landed for LU-7236 introduced new sysfs entries
which were done wrong.

1) For idle_timeout it returns -ERANGE for
   any value passed in expect setting idle_timeout to zero. This
   does not match what the commit message said for LU-7236. So
   I changed lprocfs_str_with_units_to_s64() into kstrtouint()
   since a signed 64 bit timeout is not needed. Using kstrtouint()
   ensures that negative values are not possible and also cap the
   value to CONNECTION_SWITCH_MAX since the max of 4 billion
   seconds is over kill.

2) For the next procfs idle_connect it is really a write only file
   but it was treated as both read and write. There is no need for
   the osc_idle_connect_seq_show() function.

3) Lastly no more stuffing new entries into proc or debugfs. For
   this patch convert these new proc entries to sysfs. It seems
   to be a common occurrence so add LPROC_SEQ_* to spelling.txt
   so checkpatch will complain about using LPROC_SEQ_* which will
   go away.

Change-Id: I1c992b2db47aade6a887919824d869e8d5354c71
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/32719
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>