gpio: mm-lantiq: Fix typo in the newly added header filename

The header with legacy struct of_mmio_gpio_chip and accompanying
APIs is called legacy-of-mm-gpiochip.h. Remove repetitive '.h'
at the end.

Fixes: a99cc668 ("gpiolib: split of_mm_gpio_chip out of linux/of_gpio.h")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/gpio/gpio-mm-lantiq.c

@@ -10,7 +10,7 @@
 #include <linux/platform_device.h>
 #include <linux/mutex.h>
 #include <linux/gpio/driver.h>
-#include <linux/gpio/legacy-of-mm-gpiochip.h.h>
+#include <linux/gpio/legacy-of-mm-gpiochip.h>
 #include <linux/of.h>
 #include <linux/io.h>
 #include <linux/slab.h>