LU-12072 lov: remove KEY_CACHE_SET to simplify the code

LU-12072 lov: remove KEY_CACHE_SET to simplify the code

We must invoke obd_set_info_async with KEY_CACHE_SET after
obd_connect for OSC device. In fact, It can be combined
in obd_connect to simplify the code.

Signed-off-by: Yang Sheng <ys@whamcloud.com>
Change-Id: I8cf235658a3e4af1685a7454ebfe887e5a28eccc
Reviewed-on: https://review.whamcloud.com/34419
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>