ahci: remove pmp link online check in FBS EH

ata_link_online() check in ahci_error_intr() is unnecessary, it should
be removed otherwise may lead to lockup with FBS enabled PMP.
http://marc.info/?l=linux-ide&m=137050421603272&w=2

Reported-by: Yu Liu <liuyu.ac@gmail.com>
Signed-off-by: Shane Huang <shane.huang@amd.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

drivers/ata/libahci.c

@@ -1560,8 +1560,7 @@ static void ahci_error_intr(struct ata_port *ap, u32 irq_stat)
 		u32 fbs = readl(port_mmio + PORT_FBS);
 		int pmp = fbs >> PORT_FBS_DWE_OFFSET;
 
-		if ((fbs & PORT_FBS_SDE) && (pmp < ap->nr_pmp_links) &&
-		    ata_link_online(&ap->pmp_link[pmp])) {
+		if ((fbs & PORT_FBS_SDE) && (pmp < ap->nr_pmp_links)) {
 			link = &ap->pmp_link[pmp];
 			fbs_need_dec = true;
 		}