musb_hdrc: Update peripheral side suspend support

Update peripheral side suspend support:

 - Work around some IRQ strangeness (disconnect not detected reliably
   while suspended).

 - Swaps out clearly-broken SRP logic (from Mentor?) with code which
   at least matches the documentation.

 - Track whether peripheral is suspended; this helps detect invalid remote
   wakeup requests, and will also help work around a tusb6010 peripheral
   side issue (separate patch).

 - For tusb6010, don't be so noisy with tps65030 idle/suspend messaging;
   among other things, it interferes with debugging.

 - In OTG mode, host side can now autosuspend when peripheral side is
   active (connected or otherwise).

USBCV remote wakeup tests now pass.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>