ixgbe: refactor stats register reads
ixgbe: refactor stats register reads

Move stats register reads to ixgbe_read_stats_registers() as it will be
used by the functions to retrieve stats and extended stats.

Signed-off-by: Maryam Tahhan <4186b129a1450294ee3c67173e770842b7c6caba@intel.com>
Acked-by: Olivier Matz <dfcc1510895413197abb4336e39bb0a3906cba71@6wind.com>

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