mmc: loongson2: prevent integer overflow in ret variable

In loongson2_mmc_dll_mode_init(), `ret` variable is declared
as u32 but it is expected to hold an int value.

Fixes: d0f8e96 ("mmc: loongson2: Add Loongson-2K2000 SD/SDIO/eMMC controller driver")
Reported-by: https://scan7.scan.coverity.com/#/project-view/53936/11354?selectedIssue=1644958
Signed-off-by: Sergio Perez Gonzalez <sperezglz@gmail.com>
Reviewed-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/20250707185545.46275-1-sperezglz@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: sperezglz

drivers/mmc/host/loongson2-mmc.c

@@ -485,7 +485,8 @@ static irqreturn_t loongson2_mmc_irq(int irq, void *devid)
 
 static void loongson2_mmc_dll_mode_init(struct loongson2_mmc_host *host)
 {
-	u32 val, pad_delay, delay, ret;
+	u32 val, pad_delay, delay;
+	int ret;
 
 	regmap_update_bits(host->regmap, LOONGSON2_MMC_REG_SEL,
 			   LOONGSON2_MMC_SEL_DATA, LOONGSON2_MMC_SEL_DATA);