drm/bridge: ti-sn65dsi86: Fix off-by-one error in clock choice

If the rate in our table is _equal_ to the rate we want then it's OK
to pick it.  It doesn't need to be greater than the one we want.

Fixes: a095f15c

 ("drm/bridge: add support for sn65dsi86 bridge driver")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200504213225.1.I21646c7c37ff63f52ae6cdccc9bc829fbc3d9424@changeid