kgdb: remove #include <linux/serial_8250.h> from kgdb.h

There's no reason kgdb.h itself needs to include the 8250 serial port
header file.  So push it down to the _very_ limited number of individual
drivers that need the values in that file, and fix up the places where
people really wanted serial_core.h and platform_device.h.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/video/backlight/ot200_bl.c

@@ -14,6 +14,7 @@
 #include <linux/fb.h>
 #include <linux/backlight.h>
 #include <linux/gpio.h>
+#include <linux/platform_device.h>
 #include <linux/cs5535.h>
 
 static struct cs5535_mfgpt_timer *pwm_timer;