platform/x86: mlx-platform: Rename new systems product names

Rename product names for next generation systems QMB7, SN37, SN34 to
respectively MQMB7, MSN37, MSN34.

All these systems are about to be released to the customers.
At the moment, none of them is at customers sites. The customers will
not suffer from this change.
The names have been changed due to marketing decision.

Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>