The default highest_bank_bit of 15 didn't seem to cause issues so far
but downstream defines it to be 14. But similar to [0] leaving it on 14
(or 15 for that matter) causes some corruption issues with some
resolutions with DisplayPort, like 1920x1200.

So set it to 13 for now so that there's no screen corruption.

[0] commit 6a0dbcd2 ("drm/msm/a6xx: set highest_bank_bit to 13 for a610")

Fixes: b7616b5c ("drm/msm/adreno: Add A619 support")
Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Patchwork: https://patchwork.freedesktop.org/patch/585215/Signed-off-by: Rob Clark <robdclark@chromium.org>