etraxfs_ser: QOM cast cleanups

Rename etrax_serial to ETRAXSerial, introduce type constant and use QOM
casts.

Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
xilinx_uartlite: Rename xlx_uartlite to XilinxUARTLite

Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
xilinx_uartlite: QOM cast cleanups

Introduce type constant and use QOM casts.

Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>