net/ixgbe: fix setting MTU on stopped device
net/ixgbe: fix setting MTU on stopped device

There exists case that software sets mtu (i.e jumbo frame) of
ixgbe device when it's stopped. Before the fix, scattered_rx
is cleared during device stop, and setting jumbo frame mtu
after device stop will always fail as scattered_rx is 0.

Signed-off-by: Jia Yu <34a62e20de6070542c7bca4f0f49d6e4786ad51e@vmware.com>
Acked-by: Wenzhuo Lu <58cb9036bdff9a5412edc3b9f70e105ccf59954f@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk