clk: renesas: Introduce and use rcar_clk_get_rate64_div_table function

Introduce new helper function to handle clock type that uses
clk_div_table struct. Based vaguely on Linux code. Make use
of clk_div_table in RPC clocks handling.

The E3/D3 RPCSRC need to be handled differently and will be addressed in
subsequence patch.

Based on Linux commit db4a0073cc82 ("clk: renesas: rcar-gen3: Add RPC
clocks") by Sergei Shtylyov.

Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Marek: - Squash patches to avoid adding unused code:
         clk: renesas: Make use of clk_div_table in RPC clocks handling
         clk: renesas: Introduce rcar_clk_get_rate64_div_table function
       - Move the new code to the beginning of clk-rcar-gen3 to avoid
         tables mixed with code
       - Use rcar_ prefix for get_table_div function
       - Get rid of custom macros, use GENMASK. Use custom field_get
         implementation as the generic FIELD_GET does not support
	 constant mask and u32_get_bits requires higher optimization level
       - Pass in the register bit mask instead of width/shift combination
       - Turn rcar_clk_get_rate64_div_table into s64, as it can return -EINVAL