serial: serial_pl01x: Implement .getinfo() for PL01

When ACPI is enabled on arm it will use the getinfo function to fill
the SPCR ACPI table.

Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Moritz Fischer <moritzf@google.com>

include/serial.h

@@ -124,6 +124,7 @@ enum serial_stop {
 enum serial_chip_type {
 	SERIAL_CHIP_UNKNOWN = -1,
 	SERIAL_CHIP_16550_COMPATIBLE,
+	SERIAL_CHIP_PL01X,
 };
 
 enum adr_space_type {