m68k: coldfire: use clkdev_lookup on most coldfire

Coldfire is now the only target that implements the clk_get()/clk_put()
helpers itself rather than using the common implementation.

Most coldfire variants only have two distinct clocks and use the clk
code purely for lookup. Change those over to use clkdev_lookup instead
but leave the custom clk interface for those two clocks.

Also leave the four SoCs that have gated clocks.

Acked-by: Greg Ungerer <gerg@linux-m68k.org>
Tested-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>