clk: nuvoton: Add clock driver for ma35d1 clock controller

The clock controller generates clocks for the whole chip, including
system clocks and all peripheral clocks. This driver support ma35d1
clock gating, divider, and individual PLL configuration.

There are 6 PLLs in ma35d1 SoC:
  - CA-PLL for the two Cortex-A35 CPU clock
  - SYS-PLL for system bus, which comes from the companion MCU
    and cannot be programmed by clock controller.
  - DDR-PLL for DDR
  - EPLL for GMAC and GFX, Display, and VDEC IPs.
  - VPLL for video output pixel clock
  - APLL for SDHC, I2S audio, and other IPs.
CA-PLL has only one operation mode.
DDR-PLL, EPLL, VPLL, and APLL are advanced PLLs which have 3
operation modes: integer mode, fraction mode, and spread specturm mode.

Signed-off-by: Jacky Huang <ychuang3@nuvoton.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>