Make bcm2835_clock_choose_div to optionally round up the chosen MASH divisor
so that the resulting average rate will not be higher than the requested one.
Signed-off-by: Remi Pommarel <repk@triplefau.lt>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>