Input: polldev - immediately poll device upon opening

To allow open/ioctl(EVIOCGABS)/close use pattern for polled devices read
the device in context of open() call instead of offloading the first read
to a workqueue. This will ensure that once call to open() returns device
would have cached reasonably recent axis values that can be retrieved via
appropriate ioctl.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Change-Id: I87bce80da48ee4676bf3acb2106f7561503ac279