devfreq: spdm: Fix debugfs file permissions

The files in the debugfs directory for spdm were
set incorrectly using hex instead of octal numbers.
This patch correctly uses octal codes and removes the
execute bit.

CRs-Fixed: 799304
Change-Id: I3bab83073d1ee1f426c402a05556c9ae97ca089d
Signed-off-by: Dan Sneddon <dsneddon@codeaurora.org>