LU-8238 ldlm: rid of obsolete param of ldlm_resource_get()

LU-8238 ldlm: rid of obsolete param of ldlm_resource_get()

The second parameter @parent of ldlm_resource_get() is obsolete, just
remove it.

Test-Parameters: trivial
Change-Id: I88af99c6984eda50a21da4d516ce7dea8cba60f5
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/20631
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>