ARM: davinci: Make __clk_{enable,disable} functions public

In some cases, there is a need to enable a clock as part of
clock enable callback of a different clock. For example, USB
2.0 PHY clock enable requires USB 2.0 clock to be enabled.
In this case, it is safe to instead call __clk_enable()
since the clock framework lock is already taken. Calling
clk_enable() causes recursive locking error.

A similar case arises in the clock disable path.

To enable such usage, make __clk_{enable,disable} functions
publicly available outside of clock.c. Also, call them
davinci_clk_{enable|disable} now to be consistent with how
other davinci-specific clock functions are named.

Note that these functions are not exported to drivers. They
are meant for usage in platform specific clock management
code.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Suggested-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>