thread_info: enhance power efficiency

Using cpu_relaxed_read_long and defining relaxed
version of some macros, and functions so that it
can be used to improve power efficiency.

bug 1440421

Change-Id: If857ff7110cffadc6f13289a6395d253a8e3e232
Signed-off-by: Sumit Singh <sumsingh@nvidia.com>
Reviewed-on: http://git-master/r/380859
(cherry picked from commit a66b23c6971403594cc6a82923c8df3b8472de90)
Reviewed-on: http://git-master/r/422251


Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>