mbuf: group Tx flags near end of field

mbuf: group Tx flags near end of field

This patch takes the existing TX flags defined for the mbuf and shifts
each uniquely defined one left so that additional RX flags can be
defined without having RX and TX flags mixed together. Under the new
scheme, RX flags start at bit 0 and work left, TX flags start at bit 55
and work right, and bits 56-63 are reserved for generic mbuf use, not
for offloads.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Reviewed-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>