LU-506 dcache: check lookup_instantiate_filp() return value

LU-506 dcache: check lookup_instantiate_filp() return value

For new kernels, nd->intent.open.file may not be checked before use,
but it may be an error code. To avoid this, return error when
the original open in lookup_instantiate_filp() fails.

Signed-off-by: Lai Siyao <laisiyao@whamcloud.com>
Change-Id: Ibfbc4eef284962302418872b9f1af8dce2f95db5
Reviewed-on: http://review.whamcloud.com/2491
Reviewed-by: Peng Tao <tao.peng@emc.com>
Tested-by: Hudson
Reviewed-by: Fan Yong <yong.fan@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>