musb_hdrc: Minor cleanups involving name changes

musb_hdrc: Minor cleanups involving name changes

Minor cleanups involving name changes, primarily on the peripheral side:

 - musb->bMayWakeup becomes may_wakeup (camelcase bad)
 - musb->bIsSelfPowered becomes is_self_powered (camelcase bad)
 - pThis (as parameter or variable) becomes musb (camelcase bad)
 - tusb_set_power becomes tusb_draw_power (more meaningful name)
 - tusb_set_vbus becomes tusb_source_power (more meaningful name)

Also, add a flag to track if a B-Peripheral device draws any VBUS power
(currently only tusb6010 can set that).

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