tty: serial: lantiq: Drop GPIO include

Nothing in this driver uses the symbols from <linux/gpio.h>
so drop this include.

Cc: Rahul Tanwar <[e-mail]>
Cc: Songjun Wu <[e-mail]>
Cc: Martin Blumenstingl <[e-mail]>
Cc: John Crispin <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/lantiq.c

···
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/device.h>
-#include <linux/gpio.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/ioport.h>