net: qed: use ptr shortcuts to dedup field accessing in some parts

Use intermediate pointers instead of multiple dereferencing to
simplify and beautify parts of code that will be addressed in
the next commit.

Signed-off-by: Alexander Lobakin <alobakin@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>