event/dlb2: support ldb port specific COS

event/dlb2: support ldb port specific COS

DLB supports 4 class of service domains, to aid in managing the
device bandwidth across ldb ports. This commit allows specifying
which ldb ports will participate in the COS scheme, which class
they are a part of, and the specific bandwidth percentage
associated with each class. The cumulative bandwidth associated
with the 4 classes must not exceed 100%. This feature is enabled
on the command line, and will be documented in the DLB2 programmers
guide.

Signed-off-by: Timothy McDaniel <timothy.mcdaniel@intel.com>