clk: renesas: Fix incorrect return RPC clk_get_rate

RPC clk_get_rate will return error code instead of expected clock rate.
Fix this.

Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>

drivers/clk/renesas/clk-rcar-gen3.c

@@ -310,7 +310,7 @@ static u64 gen3_clk_get_rate64(struct clk *clk)
 		      __func__, __LINE__,
 		      core->parent, prediv, postdiv, rate);
 
-		return -EINVAL;
+		return rate;
 
 	}