ARM: OMAP4/5: Centralize early clock initialization

ARM: OMAP4/5: Centralize early clock initialization

Early clock initialization is currently done in two stages for OMAP4/5
SoCs. The first stage is the initialization of console clocks and
then we initialize basic clocks for functionality necessary for SoC
initialization and basic board functionality.

By splitting up prcm_init and centralizing this clock initialization,
we setup the code for follow on patches that can do board specific
initialization such as board detection which will depend on these
basic clocks.

As part of this change, since the early clock initialization
is centralized, we no longer need to expose the console clock
initialization.

NOTE: we change the sequence slightly by initializing console clocks
timer after the io settings are complete, but this is not expected
to have any functioanlity impact since we setup the basic IO drive
strength initialization as part of do_io_settings.

Signed-off-by: Steve Kipisz <s-kipisz2@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>