drivers/net: dsa/mv88e6xxx.c files need linux/module.h

An implicit instance of module.h leaked back into existence
and was masking the fact that these drivers weren't calling
out the include for itself.  Fix the drivers before we remove
the implicit include path via net/netprio_cgroup.h file.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>