RocJpeg cmake and document fixes (#157)

- Fix for rocjpeg sample cmake due to changes in the rocJPEG project
- Fix for rocprofiler-sdk version check - change the format
- Edits to docs for jpeg and vcn activity support - mention that these values may not be supported on all ASICs.

docs/conceptual/rocprof-sys-feature-set.rst

@@ -62,6 +62,7 @@ GPU metrics
   * Utilization
   * VCN activity
   * JPEG activity
+    Note: The availability of VCN and JPEG engine activity depends on device support for different ASICs. If unsupported, all values for VCN_ACTIVITY and JPEG_ACTIVITY will be reported as N/A in the output of amd-smi metric--usage.
 
 CPU metrics
 ========================================