i2c: gpio: Fix potential unused warning for 'i2c_gpio_dt_ids'

Dropping a matching #ifdef check along with dropping of_match_ptr()
is just a cleanup, while dropping of_match_ptr() that has no
corresponding #ifdef fixes an actual warning.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>