fbnic: Rename PCS IRQ to MAC IRQ as it is actually a MAC interrupt

fbnic: Rename PCS IRQ to MAC IRQ as it is actually a MAC interrupt

Throughout several spots in the code I had called out the IRQ as being
related to the PCS. However the actual IRQ is a part of the MAC and it is
just exposing PCS data. To more accurately reflect the owner of the calls
this change makes it so that we rename the functions and values that are
taking in the interrupt value and processing it to reflect that it is a MAC
call and not a PCS one.

This change is mostly motivated by the fact that we will be moving the
handling of this interrupt from being PCS focused to being more PMA/PMD
focused as this will drive the phydev driver that I am adding instead of
driving the PCS directly.

Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://patch.msgid.link/176374322373.959489.12018231545479053860.stgit@ahduyck-xeon-server.home.arpa
Signed-off-by: Paolo Abeni <pabeni@redhat.com>