misc: fsa9480: driver for FSA USB switch

- This code is based mainstream code. but it is not submited.
- Workqueue change to request_threaded_irq.
- Remove global function & variable
- Remove Export function

Change-Id: If7d7966c594bbeb66078ee8d3e0170a890de924f
Signed-off-by: sb223.kang <sb223.kang@samsung.com>
Signed-off-by: Simon Wilson <simonwilson@google.com>

fsa9480: detect reset condition and reinit device

When the fsa9480 is reset, it will hold the interrupt line low
which will trigger an interrupt. Detect this by looking for
a zero interrupt status register, and reinitialise the device
in this case.

Signed-off-by: Simon Wilson <simonwilson@google.com>

Conflicts:
	drivers/misc/fsa9480.c
	include/linux/fsa9480.h