usb: musb: Remove try_idle for 2430 glue layer

This is no longer needed with PM runtime at least for 2430 glue.
We can now rely only on PM runtime and cable detection.

The other glue layers can probably remove try_idle too, but that
needs to be tested for each platform before doing it.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>