clk: davinci: New driver for TI DA8XX CFGCHIP clocks

This adds a new driver for the gate and multiplexer clocks in the
CFGCHIPn syscon registers on TI DA8XX-type SoCs.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>