drm/sun4i: dotclock: Allow divider = 127

drm/sun4i: dotclock: Allow divider = 127

The dot clock divider is 7 bits wide, and the divider range is 1 ~ 127,
or 6 ~ 127 if phase offsets are used. The 0 register value also
represents a divider of 1 or bypass.

Make the end condition of the for loop inclusive of 127 in the
round_rate callback.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>