NFSD: Rename a function parameter
Clean up: A function parameter called "rqstp" typically refers to an
object of type "struct svc_rqst", so it's confusing when such an
parameter refers to a different struct type with field names that are
very similar to svc_rqst.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>