tty: serial: lantiq: Drop GPIO include

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

Cc: Rahul Tanwar <rahul.tanwar@linux.intel.com>
Cc: Songjun Wu <songjun.wu@linux.intel.com>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: John Crispin <john@phrozen.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20200229212331.174946-1-linus.walleij@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/lantiq.c

@@ -11,7 +11,6 @@
 #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>