i2c: at91: mark PM ops as __maybe unused

The driver uses pm_ptr(), so the PM ops could be unused.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: dab4b0e8 ("i2c: at91: remove #define CONFIG_PM")
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Reviewed-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-at91-core.c

@@ -333,7 +333,7 @@ static int __maybe_unused at91_twi_resume_noirq(struct device *dev)
 	return 0;
 }
 
-static const struct dev_pm_ops at91_twi_pm = {
+static const struct dev_pm_ops __maybe_unused at91_twi_pm = {
 	.suspend_noirq	= at91_twi_suspend_noirq,
 	.resume_noirq	= at91_twi_resume_noirq,
 	.runtime_suspend	= at91_twi_runtime_suspend,