USB: musb: fix build when !CONFIG_PM

Fix this build error when CONFIG_PM is not set:
drivers/usb/musb/musb_core.c:2232: error: 'musb_resume_early' undeclared here

Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>