Recently few issues were noticed in the code where CONFIG_OF wasn't
consistently used for many routines. The core file is big enough now and
ifdef hackery makes it less readable.
Move OF specific code to another file and compile that only if CONFIG_OF
is enabled.
Compile-tested:
- For ARM (exynos) with CONFIG_OF enabled
- For X86 with CONFIG_OF disabled (have to enable CONFIG_PM_OPP separately)