'table' argument in bios_linker_add_foo() commands is
a data blob of one of files also passed to the same API.
So instead of passing blob in every API call, add and keep
file name association with related blob at bios_linker_loader_alloc()
time.

And find blob by name looking up allocated file entries
inside of bios_linker_add_foo() commands.

It will:
 - make API less confusing,
 - enforce calling bios_linker_loader_alloc() before
   calling any bios_linker_add_foo()
 - make sure that blob is the correct one, i.e.
   associated with the right file name
Signed-off-by: NIgor Mammedov <imammedo@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>