usb: musb: finish suspend/reset work independently from musb_hub_control()

Currently, resume and reset is completed when the USB core calls back
the root hub, asking for the port's state. This results in
unpredictable timing of state assertion, which in turn renders some
USB devices unusable after resume.

Fix this by moving the logic to end the reset and suspend state out of
musb_hub_control() into separate functions called from delayed workers.
GetPortStatus only reports the current state now, without taking any
real action.

The rh_timeout variable is kept in order to define a minimum time gap
between reset and resume only.

FWIW, in my case, a Verbatim "STORE N GO" mass storage device won't
resume cleanly without this patch.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>