Marek Vasut authored Sep 05, 2019 and Lucas Stach committed Oct 18, 2019

Replace the per-screen locking of flushing with per-context one and
add per-context lock around command stream buffer accesses, to prevent
cross-context flushing from corrupting these command stream buffers.

Signed-off-by: Marek Vasut <marex@denx.de>