community/uboot-tools: disable on ppc64le and s390x

Those arches are currently not supported.

community/uboot-tools/APKBUILD

@@ -5,7 +5,7 @@ pkgver=2019.01
 pkgrel=0
 pkgdesc="U-Boot bootloader utility tools"
 url="https://www.denx.de/wiki/U-Boot/WebHome"
-arch="all"
+arch="all !s390x !ppc64le"
 license="GPL"
 makedepends="$depends_dev bison flex openssl-dev linux-headers sdl-dev"
 options="!check" # No test suite