ixgbe/base: add macros for X550em bus speed fuse
ixgbe/base: add macros for X550em bus speed fuse

x550em has two different bus speeds, 300 MHz and 400 MHz.
A bit in a fuse register tells which it is, with a 1 meaning
the bus is running at 300 MHz.

Signed-off-by: Wenzhuo Lu <58cb9036bdff9a5412edc3b9f70e105ccf59954f@intel.com>
Acked-by: Helin Zhang <aba9dfdb1a6ec8bf1ff66b95272c029f8dfde1b1@intel.com>

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