r-b/u-boot: Add bc as dep

Observed issue was:

   /bin/sh: 1: bc: not found
   bc: not found

By the way the build script should stop on issue like this.

Relate-to: eclipse/oniro-core/oniro#542 (comment 876941)
Relate-to: meta-oniro-blueprint-flutter#4
Origin: https://gitlab.eclipse.org/pcoval/meta-seco-rockchip


Signed-off-by: Philippe Coval <philippe.coval.ext@huawei.com>

recipes-bsp/u-boot/u-boot-seco_2017.09.bb

@@ -32,7 +32,7 @@ SRCREV_FORMAT = "default_rkbin"
 DEPENDS:append = " ${PYTHON_PN}-native"
 
 # Needed for packing BSP u-boot
-DEPENDS:append = " coreutils-native ${PYTHON_PN}-pyelftools-native"
+DEPENDS:append = " bc-native coreutils-native ${PYTHON_PN}-pyelftools-native"
 
 do_configure:prepend() {
 	# Make sure we use /usr/bin/env ${PYTHON_PN} for scripts