LU-8708 osc: enable/disable OSC grant shrink

LU-8708 osc: enable/disable OSC grant shrink

Add an OSC proc interface to enable/disable client's grant shrink
feature.

lctl get_param osc.*.grant_shrink
lctl set_param osc.*.grant_shrink={0,1}

Change-Id: I7974b3bf1c4f9c294dd0d4871d09b1a2e45a8d78
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/23203
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>