clk: keystone: syscon-clk: Allow the clock node to not be of type syscon

There is a helper device_node_to_regmap() we can use that does not force
this clock DT node to be a "syscon" node. It should work the same in
this case but allow us to remove the unneeded "syscon" compatible.

Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20230516184626.154892-1-afd@ti.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>