Add support for CPLD4 for the next generation systems MQMB7xx, MSN37xx,
MSN34xx, MSN38xx.

All these systems are equipped with four programmable device.
The version of this new device is to be exposed to sysfs through
mlxreg-io register.
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>