tsens: fix compilation when CONFIG_DEBUG_FS is disabled

Fix compilation error when CONFIG_DEBUG_FS is disabled in
perf_defconfig.

Change-Id: Ia29dfa0f8b8209455f19474952e6ede6b8b11b5c
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
[rshaha@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Rahul Shahare <rshaha@codeaurora.org>