i40e: Drop redundant Rx descriptor processing code

i40e: Drop redundant Rx descriptor processing code

This patch cleans up several pieces of redundant code in the Rx clean-up
paths.

The first bit is that hdr_addr and the status_err_len portions of the Rx
descriptor represent the same value.  As such there is no point in setting
them to 0 before setting them to 0.  I'm dropping the second spot where we
are updating the value to 0 so that we only have 1 write for this value
instead of 2.

The second piece is the checking for the DD bit in the packet.  We only
need to check for a non-zero value for the status_err_len because if the
device is done with the descriptor it will have written something back and
the DD is just one piece of it.  In addition I have moved the reading of
the Rx descriptor bits related to rx_ptype down so that they are actually
below the dma_rmb() call so that we are guaranteed that we don't have any
funky 64b on 32b calls causing any ordering issues.

Change-ID: I256e44a025d3c64a7224aaaec37c852bfcb1871b
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>