staging/rdma/hfi1: Make EPROM check per device

Add a variable eprom_available to each device, replacing the
global of the same name.  This is to allow multiple HFI devices
with different EPROM availability to operate correctly on the
the same system.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Jubin John <jubin.john@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>