mips/bootm: Fix typo in commit c4f9419c, "initrd_start" replaced by "images->rd_start"

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

lib_mips/bootm.c

@@ -73,7 +73,7 @@ int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
 	linux_env_set ("memsize", env_buf);
 
 	sprintf (env_buf, "0x%08X", (uint) UNCACHED_SDRAM (images->rd_start));
-	linux_env_set ("images->rd_start", env_buf);
+	linux_env_set ("initrd_start", env_buf);
 
 	sprintf (env_buf, "0x%X", (uint) (images->rd_end - images->rd_start));
 	linux_env_set ("initrd_size", env_buf);