clk: at91: clk-main: drop parent_name check when registering main_rc oscillator

The clk_register function logs an error if parent_name is missing from the
Device Tree.On the SAM9X7, the main_rc node is omitted to stay aligned with
the Linux Device Tree.Remove the parent_name check in at91_clk_main_rc()
to allow it to pass NULL when the parent is not specified.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>

drivers/clk/at91/clk-main.c

@@ -110,7 +110,7 @@ struct clk *at91_clk_main_rc(void __iomem *reg, const char *name,
 	struct clk *clk;
 	int ret;
 
-	if (!reg || !name || !parent_name)
+	if (!reg || !name)
 		return ERR_PTR(-EINVAL);
 
 	main_rc = kzalloc(sizeof(*main_rc), GFP_KERNEL);