ixgbe: cleanup race conditions in link setup

This change makes it so that we perform link setup with interrupts
disabled. If the SFP has not been detected previously we will schedule the
SFP detection task to run in order to detect link.  By doing this we avoid
the possibility of interrupts firing in the middle of our link setup during
ixgbe_up_complete.

In addition this change makes it so that the multi-speed fiber setup and SFP
setup are not mutually exclusive.  The addresses issues seen in which a
link would only come up at 1G on some multi-speed fiber modules.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>