Remove --enable-viewport-meta switch on embedded

This breaks the initial scale of some pages on embedded Linux
and is mostly tied to Android codepaths in chromium and might
be removed soon from public switches.

See: https://code.google.com/p/chromium/issues/detail?id=513214
and: https://code.google.com/p/chromium/issues/detail?id=232102



Change-Id: I9eb6577bcc9c3aeb583ac6576e9de34c230c36c3
Reviewed-by: Peter Varga <pvarga@inf.u-szeged.hu>