ath79: gpio-latch: fix compilation warning for wrong dev_err %

ath79: gpio-latch: fix compilation warning for wrong dev_err %

Fix compilation warning for using %d instead of %ld for gpio-latch in
dev_err.
Fix compilation warning:
In file included from ./include/linux/device.h:15,
                 from ./include/linux/gpio/driver.h:5,
                 from drivers/gpio/gpio-latch.c:13:
drivers/gpio/gpio-latch.c: In function 'gpio_latch_probe':
drivers/gpio/gpio-latch.c:137:46: error: format '%d' expects argument of type 'int', but argument 4 has type 'long int' [-Werror=format=]
  137 |                                 dev_err(dev, "failed to get gpio %d: %d\n", i,
      |                                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/dev_printk.h:110:30: note: in definition of macro 'dev_printk_index_wrap'
  110 |                 _p_func(dev, fmt, ##__VA_ARGS__);                       \
      |                              ^~~
./include/linux/dev_printk.h:144:56: note: in expansion of macro 'dev_fmt'
  144 |         dev_printk_index_wrap(_dev_err, KERN_ERR, dev, dev_fmt(fmt), ##__VA_ARGS__)
      |                                                        ^~~~~~~
drivers/gpio/gpio-latch.c:137:33: note: in expansion of macro 'dev_err'
  137 |                                 dev_err(dev, "failed to get gpio %d: %d\n", i,
      |                                 ^~~~~~~
drivers/gpio/gpio-latch.c:137:71: note: format string is defined here
  137 |                                 dev_err(dev, "failed to get gpio %d: %d\n", i,
      |                                                                      ~^
      |                                                                       |
      |                                                                       int
      |                                                                      %ld
cc1: all warnings being treated as errors

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>