ice: Create a generic name for the ice_rx_flg64_bits structure

This structure is used to define the packet flags. These flags are
applicable for both TX and RX packet. Thus, this patch changes its
name from ice_rx_flag64_bits to ice_flg64_bits, and its member definition.

Signed-off-by: Chinh T Cao <chinh.t.cao@intel.com>
Reviewed-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>