x86: Fix PCI UART compatible string for crownbay and galileo

With recent ns16550 driver changes, we only changed the legacy UART
(at I/O port 0x3f8) compatible string, but forgot to change the PCI
UART compatible string. Now fix it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>