UPSTREAM: ARM: socfpga_defconfig: Add back DEBUG_FS

Commit 0e4a459f56c3 ("tracing: Remove unnecessary DEBUG_FS dependency")
removed select for DEBUG_FS but we still need it for development purposes.

Fixes: 0e4a459f56c3 ("tracing: Remove unnecessary DEBUG_FS dependency")
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
(cherry picked from commit 41bae0caf5dc216c7b43712b8c2b6a0d63b4d655)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I43ec65bdd0d67d9a3be986c8ccc2e86eed1763fa