mcb: Fixed bar number assignment for the gdd

The bar number is found in reg2 within the gdd. Therefore
we need to change the assigment from reg1 to reg2 which
is the correct location.

Signed-off-by: Andreas Werner <andreas.werner@men.de>
Fixes: '3764e82e' drivers: Introduce MEN Chameleon Bus
Cc: stable@vger.kernel.org # v3.15+
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>