Input: mpu3050 - ensure we enable interrupts

This also changes the devname parameter delivered to
request_threaded_irq() from "mpu_int" to "mpu3050".

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>