msm: kgsl: Fix adreno_cmdbatch_retired tracepoint format

The adreno_cmdbatch_retired tracepoint originally used the string
"ctx_prio". This changed when adding dispatch on GMU support to
"prio". Changing this back to the original so that external parsers
are not impacted.

Change-Id: I89010509ac4cc0db03fcdee302bbe28db604f66c
Signed-off-by: Sushmita Susheelendra <ssusheel@codeaurora.org>