msm: kgsl: Add and link gpu sysfs nodes

Add new sysfs nodes which satisfy a generic format requested
by customer. Also add a new node to track GPU temperature.
Create links to these nodes at a generic location:

/sys/kernel/gpu/

CRs-Fixed: 1064728
Change-Id: I414a07ff4f9ee14b8f882d15644b06a73d5fcf76
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>
Signed-off-by: Sunil Khatri <sunilkh@codeaurora.org>