m68k: coldfire: remove private clk_get/clk_put

Only three SoCs remain that use the custom clk_get/clk_put.
Move these over to clkdev_lookup tables as well. As before,
treat the "sys.0" and "pll.0" clocks as system-wide clocks,
and all the other ones as device specific.

The "name" field in 'struct clock' is now unused, so rename
that as well as a cleanup and to reduce the object code size.
The DEFINE_CLK macro could be changed the same way, but it
is less churn to just leave those in place, that can be
done as a follow-up later if someone is interested.

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