libata: remove ATA_FLAG_MMIO

Commit 0d5ff566779f894ca9937231a181eb31e4adff0e (libata: convert to iomap)
removed all checks of ATA_FLAG_MMIO but neglected to remove the flag itself.
Do it now, at last...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/pata_at32.c b/drivers/ata/pata_at32.c
index 66ce6a5..36f189c 100644
--- a/drivers/ata/pata_at32.c
+++ b/drivers/ata/pata_at32.c
@@ -194,7 +194,7 @@
 	/* Setup ATA bindings */
 	ap->ops	     = &at32_port_ops;
 	ap->pio_mask = PIO_MASK;
-	ap->flags   |= ATA_FLAG_MMIO | ATA_FLAG_SLAVE_POSS;
+	ap->flags   |= ATA_FLAG_SLAVE_POSS;
 
 	/*
 	 * Since all 8-bit taskfile transfers has to go on the lower