FIX: [gles] do not force vsync off if VSYNC_DRIVER

This solves the bug that we are forcing a vsync mode in "Driver" mode (actually we are disabling vsync as m_iVSyncMode stays at 0, then).

Generally speaking, I wonder if we need this at all, as we are apparently setting the vsync for each and every frame in Application.cpp:2239

/cc @davilla @t-nelson