drm/i915/dp: increase i2c-over-aux retry interval on AUX DEFER

commit 8d16f258217f2f583af1fd57c5144aa4bbe73e48 upstream.

There is no clear cut rules or specs for the retry interval, as there
are many factors that affect overall response time. Increase the
interval, and even more so on branch devices which may have limited i2c
bit rates.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reference: https://bugs.freedesktop.org/show_bug.cgi?id=60263
Tested-by: Nicolas Suzor <nic@suzor.com>
Reviewed-by: Todd Previte <tprevite@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>