mmc: add prototype for mmc_get_env_addr

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
diff --git a/include/mmc.h b/include/mmc.h
index 7f5f9bc..d74a190 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -387,6 +387,7 @@
 
 int board_mmc_init(bd_t *bis);
 int cpu_mmc_init(bd_t *bis);
+int mmc_get_env_addr(struct mmc *mmc, int copy, u32 *env_addr);
 
 /* Set block count limit because of 16 bit register limit on some hardware*/
 #ifndef CONFIG_SYS_MMC_MAX_BLK_COUNT