u-boot: Move B from u-boot.inc to u-boot-common.inc

Use the same value of B between u-boot and u-boot-tools.
This patch also enable the out-of-tree builds of u-boot-tools actually.

(From OE-Core rev: 26023b6b0f897842fd98b3e10a8acd5b3ad8f418)

Signed-off-by: Daisuke Yamane <yamane07ynct@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-bsp/u-boot/u-boot-common.inc

@@ -18,3 +18,5 @@ SRC_URI = "git://git.denx.de/u-boot.git \
           "
 
 S = "${WORKDIR}/git"
+B = "${WORKDIR}/build"
+do_configure[cleandirs] = "${B}"

meta/recipes-bsp/u-boot/u-boot.inc

@@ -1,8 +1,6 @@
 SUMMARY = "Universal Boot Loader for embedded devices"
 PROVIDES = "virtual/bootloader"
 
-B = "${WORKDIR}/build"
-
 PACKAGE_ARCH = "${MACHINE_ARCH}"
 
 DEPENDS += "kern-tools-native"