spl: spl_mmc: fix mmc Falcon mode regression

91199f4a broke mmc based Falcon mode.

The block_read function returns the number of blocks read thus the error
check needs to look for a return of 0 blocks read.

Cc: Paul Kocialkowski <contact@paulk.fr>
Signed-off-by: NTim Harvey <tharvey@gateworks.com>
Acked-by: NPaul Kocialkowski <contact@paulk.fr>

common/spl/spl_mmc.c

@@ -76,7 +76,7 @@ static int mmc_load_image_raw_os(struct mmc *mmc)
 					CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
 					CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS,
 					(void *)CONFIG_SYS_SPL_ARGS_ADDR);
-	if (err) {
+	if (err == 0) {
 #ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
 		printf("spl: mmc block read error\n");
 #endif