mmc: fix return value check condition

sd_read_ssr returns 0, means no error.
Fixes: 5b2e72f3("mmc: read ssr only if MMC write support is enabled")
Signed-off-by: NPeng Fan <peng.fan@nxp.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Jean-Jacques Hiblot <jjhiblot@ti.com>

drivers/mmc/mmc.c

@@ -1689,7 +1689,7 @@ static int sd_select_mode_and_width(struct mmc *mmc, uint card_caps)
 
 #if CONFIG_IS_ENABLED(MMC_WRITE)
 				err = sd_read_ssr(mmc);
-				if (!err)
+				if (err)
 					pr_warn("unable to read ssr\n");
 #endif
 				if (!err)