IB/ipath: Correct checking of swminor version field when using subports

When subports are required to run a program, this patch checks that
the driver and the userspace library have compatible subport
implementations.  This is achieved through checks on the swminor
version field built into the driver and userspace library.  Bad
combinations are reported through syslog and result in an error when
opening the port.

Signed-off-by: Mark Debbage <mark.debbage@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>