nand_spl: remove nand_spl infrastructure

Remove the common infrastructure of nand_spl and
clean-up the code inside ifdef(CONFIG_NAND_U_BOOT)..endif.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/common/env_embedded.c b/common/env_embedded.c
index 1c4f915..56a13cb 100644
--- a/common/env_embedded.c
+++ b/common/env_embedded.c
@@ -33,7 +33,7 @@
  * a seperate section.  Note that ENV_CRC is only defined when building
  * U-Boot itself.
  */
-#if (defined(CONFIG_SYS_USE_PPCENV) || defined(CONFIG_NAND_U_BOOT)) && \
+#if defined(CONFIG_SYS_USE_PPCENV) && \
 	defined(ENV_CRC) /* Environment embedded in U-Boot .ppcenv section */
 /* XXX - This only works with GNU C */
 #  define __PPCENV__	__attribute__ ((section(".ppcenv")))