soc/tegra: pmc: Change to use DEFINE_SHOW_ATTRIBUTE macro

Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/soc/tegra/pmc.c

@@ -752,17 +752,7 @@ static int powergate_show(struct seq_file *s, void *data)
 	return 0;
 }
 
-static int powergate_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, powergate_show, inode->i_private);
-}
-
-static const struct file_operations powergate_fops = {
-	.open = powergate_open,
-	.read = seq_read,
-	.llseek = seq_lseek,
-	.release = single_release,
-};
+DEFINE_SHOW_ATTRIBUTE(powergate);
 
 static int tegra_powergate_debugfs_init(void)
 {