aspeed: u-boot: Add dependencies on flex/bison

Backport oe-core 71309a5c91209d4afaee874889fa7eefb266185f to our
recipes:

  u-boot: Add missing dependency on flex and bison native

  The U-Boot build, in particular the Kconfig, depends on bison and
  flex native. Add the missing dependencies.

  Signed-off-by: Marek Vasut <marex@denx.de>
  Cc: Alexander Kanavin <alexander.kanavin@linux.intel.com>
  Cc: Otavio Salvador <otavio@ossystems.com.br>
  Cc: Richard Purdie <richard.purdie@linuxfoundation.org>
  Cc: Ross Burton <ross.burton@intel.com>
  Signed-off-by: Ross Burton <ross.burton@intel.com>

(From meta-aspeed rev: ff2e4ed2f8f642fe54ac094c02c22166d8ee3131)

Change-Id: Icd04ad815c63149af6033d1419a1a2e180e1b728
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-aspeed/recipes-bsp/u-boot/u-boot-fw-utils-aspeed_2016.07.bb b/meta-aspeed/recipes-bsp/u-boot/u-boot-fw-utils-aspeed_2016.07.bb
index 713133c..e9f724d 100644
--- a/meta-aspeed/recipes-bsp/u-boot/u-boot-fw-utils-aspeed_2016.07.bb
+++ b/meta-aspeed/recipes-bsp/u-boot/u-boot-fw-utils-aspeed_2016.07.bb
@@ -5,7 +5,7 @@
 SRC_URI += "file://alt_fw_env.config"
 
 SUMMARY = "U-Boot bootloader fw_printenv/setenv utilities"
-DEPENDS = "mtd-utils"
+DEPENDS += "mtd-utils"
 
 PROVIDES += "u-boot-fw-utils"