If the I2C device provides an interrupt it is registered and the
standard
is updated via interrupts rather than polling.

Since I2C communication is needed, the interrupt handler fires off a
work which will check the new standard, and store it in the internal
structure.

To handle mutual exclusion a mutex is introduced.
Signed-off-by: Richard Röjfors <richard.rojfors@mocean-labs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>