NFSD: remove redundant variable status

Return value directly from fh_verify() do_open_permission()
exp_pseudoroot() instead of getting value from
redundant variable status.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Jinpeng Cui <cui.jinpeng2@zte.com.cn>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>