mfd: iqs62x: Provide device revision to sub-devices

Individual sub-devices may elect to make decisions based on the
specific revision of silicon encountered at probe. This data is
already read from the device, but is not retained.

Pass this data on to the sub-devices by adding the software and
hardware numbers (registers 0x01 and 0x02, respectively) to the
iqs62x_core struct.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>