CHROMIUM: drm: Allow 5 tries when probing DDC

CHROMIUM: drm: Allow 5 tries when probing DDC

Some monitors consistently NAK the first EDID read request when connected
over a DVI-DP cable.  Thus, allow five NAK failures before giving up when
probing.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
BUG=chromium-os:31301
TEST=Hot plug DP/DVI cable into lumpy;
TEST=Should show display on both monitors.

Change-Id: I339dde875893bddb9fb65bcf277993493aa56f20
Reviewed-on: https://gerrit.chromium.org/gerrit/27634
Tested-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Simon Que <sque@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Commit-Ready: <marcheu@google.com>