libata: fix EH action overwriting in ata_eh_reset()

ehc->i.action got accidentally overwritten to ATA_EH_HARD/SOFTRESET in
ata_eh_reset().  The original intention was to clear reset action
which wasn't selected.  This can cause unexpected behavior when other
EH actions are scheduled together with reset.  Fix it.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-eh.c

@@ -2251,10 +2251,10 @@ int ata_eh_reset(struct ata_link *link, int classify,
 	ehc->i.action &= ~ATA_EH_RESET;
 	if (hardreset) {
 		reset = hardreset;
-		ehc->i.action = ATA_EH_HARDRESET;
+		ehc->i.action |= ATA_EH_HARDRESET;
 	} else if (softreset) {
 		reset = softreset;
-		ehc->i.action = ATA_EH_SOFTRESET;
+		ehc->i.action |= ATA_EH_SOFTRESET;
 	}
 
 	if (prereset) {