qt5location: fix plugins build dependency

Do not build the plugins before the dependency on module positioning for
the plugin subdir position is available (add Add upstream patch
0001-Fix-plugins-build-dependency.patch [1]).

Fixes [2]:

  cp -dpfr .../output/host/aarch64-buildroot-linux-gnu/sysroot/usr/lib/qt/plugins/position .../output/target/usr/lib/qt/plugins/
  cp: cannot stat '.../output/host/aarch64-buildroot-linux-gnu/sysroot/usr/lib/qt/plugins/position': No such file or directory

[1] https://code.qt.io/cgit/qt/qtlocation.git/patch/?id=3ac051c4549575634cecc706175b019f4ed4c3bf
[2] http://autobuild.buildroot.net/results/bc1/bc13abf3bb2fe1c991aec2334ee658c9641d1fd5



Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>