mlx4: update documentation for MOFED 3.0
mlx4: update documentation for MOFED 3.0

- Add RX/TX L3/L4 checksum offloading and validation.
- Update kernel module parameters section.
- Update prerequisites for MOFED and firmware versions.
- Remove optimized external libraries section. MOFED now provides enhanced
  support directly without having to install modified libraries.

Signed-off-by: Adrien Mazarguil <9d39ea493ca46c560334f650ac5d4b5ffbcb5cf0@6wind.com>

john-mcnamara-intel/dpdk,mixja/dpdk,john-mcnamara-intel/dpdk,mixja/dpdk,msune/dpdk,msune/dpdk,tsphillips/dpdk-fork,tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,msune/dpdk,venkynv/dpdk-mirror,venkynv/dpdk-mirror,venkynv/dpdk-mirror,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,mixja/dpdk,tsphillips/dpdk-fork,msune/dpdk,tsphillips/dpdk-fork,mixja/dpdk