IB/mthca: Fix max_sge value returned by query_device
IB/mthca: Fix max_sge value returned by query_device

The mthca driver returns the maximum number of scatter/gather entries
returned by the firmware as the max_sge value when device properties
are queried.  However, the firmware also reports a limit on the
maximum descriptor size allowed, and because mthca takes into account
the worst case send request overhead when checking whether to allow a
QP to be created, the largest number of scatter/gather entries that
can be used with mthca may be limited by the maximum descriptor size
rather than just by the actual s/g entry limit.

This means that applications cannot actually create QPs with
max_send_sge equal to the limit returned by ib_query_device().  Fix
this by checking if the maximum descriptor size imposes a lower limit
and if so returning that lower limit.

Signed-off-by: Roland Dreier <91e9b5f7ca0bb6300133ed378670d64af90dde66@cisco.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas