ARM: OMAP: clock: list all clk_hw_omap clks to enable/disable autoidle

Platforms can call omap2_init_clk_hw_omap_clocks() to register a clock
using clk_hw_omap. omap2_clk_enable_autoidle_all() and
omap2_clk_disable_autoidle_all() can then be used to run through
all the clocks which support autoidle to enable/disable them.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Mike Turquette <mturquette@ti.com>
[paul@pwsan.com: added kerneldoc on non-trivial new functions]
Signed-off-by: Paul Walmsley <paul@pwsan.com>