intel-ci/fast-feedback.testlist: Add debugfs_test@sysfs

Add debugfs_test@sysfs subtest to i915 fast feedback testlist
to improve validation if any changes are added in sysfs node.

Signed-off-by: Aditya Chauhan <aditya.chauhan@intel.com>
Acked-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>