net/ice/base: fix rate limit burst size calculation

net/ice/base: fix rate limit burst size calculation

When the MSB is not set, the lower 11 bits do not represent bytes, but
chunks of 64 bytes. Adjust the rate limit burst size calculation
accordingly, and update the comments to indicate the way the hardware
actually works.

Fixes: 93e84b1bfc92 ("net/ice/base: add basic Tx scheduler")
Cc: stable@dpdk.org
Signed-off-by: Ben Shelton <benjamin.h.shelton@intel.com>
Signed-off-by: Paul M Stillwell Jr <paul.m.stillwell.jr@intel.com>
Signed-off-by: Leyi Rong <leyi.rong@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>