meta-openpli: don't build gst-plugin-subsink for MACHINE_ARCH

By removing MACHINE_ARCH plugin will be build using the default TUNE_PKGARCH.

Signed-off-by: Erik Slagter <erik@openpli.org>
mut@nt: update bsp

commit 5e9beed
Author: HD-Digital <hd.stb.digital@gmail.com>
Date:   Mon Dec 8 20:57:04 2014 +0100

    fix image build
Merge branch 'master' of git://git.code.sf.net/p/openpli/openpli-oe-core