ahci: Don't start command DMA engine before buffers are set

The DMA/FIS buffers are set in ahci_port_start() which is called
after ahci_host_init(). So don't start the DMA engine here
(i.e. don't set FIS_RX)

This fixes the following error at kernel boot on OMAP platforms (e.g. DRA7x)
WARNING: CPU: 0 PID: 0 at drivers/bus/omap_l3_noc.c:147 l3_interrupt_handler+0x260/0x358()
44000000.ocp:L3 Custom Error: MASTER SATA TARGET GPMC (Idle): Data Access in User mode during Functional access

Signed-off-by: Roger Quadros <rogerq@ti.com>

drivers/block/ahci.c

@@ -229,7 +229,6 @@ static int ahci_host_init(struct ahci_probe_ent *probe_ent)
 		 * already be on in the command register.
 		 */
 		cmd = readl(port_mmio + PORT_CMD);
-		cmd |= PORT_CMD_FIS_RX;
 		cmd |= PORT_CMD_SPIN_UP;
 		writel_with_flush(cmd, port_mmio + PORT_CMD);