RDS: Remove cond_resched() in RX tasklet

RDS: Remove cond_resched() in RX tasklet

Re-install the base fix 17829338 and replace
spin_lock_irqsave(rx_lock)/spin_unlock_ireqrestore(rx_lock) with
spin_lock_bh(rx_lock)/spin_unlock_bh(rx_lock) to resolve bugs 18413711
and 18461816.  rx_lock is used to prevent concurrent reaping b/w the
RX tasklet and worker.

Orabug: 18801937

Signed-off-by: Bang Nguyen <bang.nguyen@oracle.com>
Signed-off-by: Chien-Hua Yen <chien.yen@oracle.com>
Tested-by: Arvind Shukla <arvind.shukla@oracle.com>
(cherry picked from commit 409138bae9be49ee9782eed244a20774d61d6208)
Signed-off-by: Jerry Snitselaar <jerry.snitselaar@oracle.com>
(cherry picked from commit cb2cb09bc520f2915a7c9c2eb1072d936a7b64b6)