env_nand: use nand_spl_load_image for readenv if SPL

The readenv() implementation of env_nand uses the mtd layer which is
unnecessary overhead in SPL when we already have a nand_spl_load_image()
function that doesn't need it. Using this instead eliminates the need
to provide a mtd_read for SPL env as well as reduces code (4KB savings in IMX6
SPL).

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Acked-by: Scott Wood <scottwood@freescale.com>

common/env_nand.c

@@ -233,6 +233,12 @@ int saveenv(void)
 }
 #endif /* CMD_SAVEENV */
 
+#if defined(CONFIG_SPL_BUILD)
+static int readenv(size_t offset, u_char *buf)
+{
+	return nand_spl_load_image(offset, CONFIG_ENV_SIZE, buf);
+}
+#else
 static int readenv(size_t offset, u_char *buf)
 {
 	size_t end = offset + CONFIG_ENV_RANGE;
@@ -266,6 +272,7 @@ static int readenv(size_t offset, u_char *buf)
 
 	return 0;
 }
+#endif /* #if defined(CONFIG_SPL_BUILD) */
 
 #ifdef CONFIG_ENV_OFFSET_OOB
 int get_nand_env_oob(nand_info_t *nand, unsigned long *result)