pds_core: remove CONFIG_DEBUG_FS from makefile

This cruft from previous drafts should have been removed when
the code was updated to not use the old style dummy helpers.

Fixes: 55435ea7

 ("pds_core: initial framework for pds_core PF driver")
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>