ARM: uniphier: add PLL init code for LD11 SoC

 - Initialize PLLs (SPL initializes only DPLL to save the precious
   SPL memory footprint)
 - Adjust CPLL/MPLL to the final tape-out frequency
 - Set the Cortex-A53 clock to the maximum frequency since it is
   running at 500MHz (SPLL/4) on startup

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>