OMAP2+: clock: add interface clock type code with autoidle support

OMAP2+: clock: add interface clock type code with autoidle support

Add interface clock type code with autoidle enable/disable support.
The clkops structures created in this file will be used for all
OMAP2/3 interface clocks with autoidle support.  They will enable the
clock framework to control interface clock autoidle directly.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Rajendra Nayak <rnayak@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>