serial: 8250_exar: Don't use "proxy" headers

Update header inclusions to follow IWYU (Include What You Use)
principle.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240219150627.2101198-8-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_exar.c

@@ -6,20 +6,24 @@
  *
  *  Copyright (C) 2017 Sudip Mukherjee, All Rights Reserved.
  */
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/device.h>
 #include <linux/dmi.h>
+#include <linux/interrupt.h>
 #include <linux/io.h>
-#include <linux/kernel.h>
+#include <linux/math.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/pm.h>
 #include <linux/property.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
+#include <linux/serial_8250.h>
 #include <linux/serial_core.h>
 #include <linux/serial_reg.h>
-#include <linux/slab.h>
-#include <linux/string.h>
-#include <linux/tty.h>
-#include <linux/delay.h>
 
 #include <asm/byteorder.h>