mmc: loongson2: Fix error code in loongson2_mmc_resource_request()

There is a cut and paste bug so we accidentally return the wrong
variable. It should be "ret" instead of PTR_ERR(host->clk).

Fixes: 2115772014bd ("mmc: loongson2: Add Loongson-2K SD/SDIO controller driver")
Signed-off-by: Dan Carpenter <[e-mail]>
Reviewed-by: Binbin Zhou <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/mmc/host/loongson2-mmc.c

···
 	if (host->clk) {
 		ret = devm_clk_rate_exclusive_get(dev, host->clk);
 		if (ret)
-			return PTR_ERR(host->clk);
+			return ret;
 
 		host->current_clk = clk_get_rate(host->clk);
 	} else {