cpufreq: interactive: clean up sysfs declarations

Cosmetics: introducing a macro to define unsigned long sysfs nodes.

Change-Id: I594a527dc977437405167237e8d5ac6d3a3167d2
Signed-off-by: Ilan Aelion <iaelion@nvidia.com>
Reviewed-on: http://git-master/r/113020
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Matthew Longnecker <mlongnecker@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>