dm: serial: Introduce ->getinfo() callback

New callback will give a necessary information to fill up ACPI SPCR table,
for example. Maybe used later for other purposes.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Change ADR_SPACE_SYSTEM_IO to SERIAL_ADDRESS_SPACE_IO to fix build error:
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/common.h b/include/common.h
index 5747836..20c99da 100644
--- a/include/common.h
+++ b/include/common.h
@@ -357,6 +357,8 @@
 void smp_kick_all_cpus(void);
 
 /* $(CPU)/serial.c */
+struct serial_device_info;
+
 int	serial_init   (void);
 void	serial_setbrg (void);
 void	serial_putc   (const char);
@@ -366,6 +368,7 @@
 int	serial_tstc   (void);
 int	serial_getconfig(uint *config);
 int	serial_setconfig(uint config);
+int	serial_getinfo(struct serial_device_info *info);
 
 /* $(CPU)/speed.c */
 int	get_clocks (void);