commit bca9690 Linux upstream adjusted
to current Barebox codebase.

  clk: divider: Make generic for usage elsewhere

  Some devices don't use mmio to interact with dividers. Split out the
  logic from the register read/write parts so that we can reuse the
  division logic elsewhere.

  Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
  Tested-by: Kenneth Westfield <kwestfie@codeaurora.org>
  Signed-off-by: Michael Turquette <mturquette@linaro.org>

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>