usb/isp1760: Move some code (prepare for next patch)

Move the few lines of code in isp1760_enable_interrupts() and
isp1760_init_maps() into isp1760_run(). This makes the following patch
easier.

Signed-off-by: Arvid Brodin <arvid.brodin@enea.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>