drivers: nfc: nfcsim: remove return value check of `dev_dir`

Smatch complains that:
nfcsim_debugfs_init_dev() warn: 'dev_dir' is an error pointer or valid

According to the documentation of the debugfs_create_dir() function,
there is no need to check the return value of this function.
Just delete the dead code.
Signed-off-by: Jianuo Kuang <u202110722@hust.edu.cn>
Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230424024140.34607-1-u202110722@hust.edu.cnSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/nfc/nfcsim.c

@@ -367,11 +367,6 @@ static void nfcsim_debugfs_init_dev(struct nfcsim *dev)
 	}
 
 	dev_dir = debugfs_create_dir(devname, nfcsim_debugfs_root);
-	if (!dev_dir) {
-		NFCSIM_ERR(dev, "Could not create debugfs entries for nfc%d\n",
-			   idx);
-		return;
-	}
 
 	debugfs_create_u8("dropframe", 0664, dev_dir, &dev->dropframe);
 }