ARC: clk: introduce HSDK pll driver

ARC: clk: introduce HSDK pll driver

HSDK board manages its clocks using various PLLs. These PLL have same
dividers and corresponding control registers mapped to different addresses.
So we add one common driver for such PLLs.

Each PLL on HSDK board consists of three dividers: IDIV, FBDIV and
ODIV. Output clock value is managed using these dividers.

We add pre-defined tables with supported rate values and appropriate
configurations of IDIV, FBDIV and ODIV for each value.

As of today we add support for PLLs that generate clock for the
HSDK arc cpus, system, ddr, AXI tunnel and hdmi.

By this patch we add support for several plls (arc cpus pll and others),
so we had to use two different init types: CLK_OF_DECLARE for arc cpus pll
and regular probing for others plls.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>