serial: 8250_dw: Set FIFO size dynamically

Designware UART provides optional Component Parameter
Register that lists most of the capabilities of the UART,
including FIFO size. This uses that register to set FIFO
size for the port before registering it.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>