serial: pl011: remove redundant early amba_ports declaration

This early amba_ports declaration was introduced by commit c16d51a3 (amba
pl011: workaround for uart registers lockup) for use in the pl011_lockup_wa()
routine. This routine was later removed by commit 4fd0690b (serial: pl011:
implement workaround for CTS clear event issue).

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>