usb: musb: don't leave PHY enabled on shutdown()

usb: musb: don't leave PHY enabled on shutdown()

Some actions like musb_platform_exit are only performed on module
removal and not on shutdown, which results in PHY being left enabled
on reboot at least. This is sometimes causing strange failures after
reboot (observed on OMAP3 pandora board), when DEVCTL does not report
VBUS state correctly due to unknown reasons (possibly because of
communication issues between musb IP and PHY). Running
musb_platform_exit before reset seems to resolve that issue.

Move some exit code from musb_remove() to musb_shutdown() so that it
is performed on both module removal and shutdown/reset. Also convert
the host check so that it doesn't need #ifdef.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>