USB: musb: only print info message if probe() is successful

we were printing the info about musb probe too early where
it was still possible for things to go wrong. Move the
down right before the return 0 statement. While at that
also convert pr_info to dev_info.

Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>