msm: kgsl: Create first_open and last_close

As the name suggests, the first_open is called when the device
is opened for the first time. And last_close is called when last
device instance is closed. This helps with differentiating eCP
and non eCP open within adreno namespace.

Change-Id: Idfbb487313d8be4de9d9785dbcdfb479dbab969e
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>