hwspinlock: sprd: fixed warning of unused variable 'sprd_hwspinlock_of_match'

The macro function of_match_ptr() is NULL if CONFIG_OF is not set, in this
case Clang compiler would complain the of_device_id variable is unused.

Reviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Fixes: d8c8bbbb1a ("hwspinlock: sprd: Add hardware spinlock driver")
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lore.kernel.org/r/20201112070410.14810-1-zhang.lyra@gmail.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/hwspinlock/sprd_hwspinlock.c

@@ -146,7 +146,7 @@ static struct platform_driver sprd_hwspinlock_driver = {
 	.probe = sprd_hwspinlock_probe,
 	.driver = {
 		.name = "sprd_hwspinlock",
-		.of_match_table = of_match_ptr(sprd_hwspinlock_of_match),
+		.of_match_table = sprd_hwspinlock_of_match,
 	},
 };
 module_platform_driver(sprd_hwspinlock_driver);