Userspace will set a flag in the context if preambles are in use. If they are, we can safely skip save and restore commands for the context. GMEM save/restore is still required. To improve performance, preamble commands are skipped when the context hasn't changed since the last issueibcmds. Change-Id: I21bb8996d62651122dbebcf7a79543679109e1f9 Signed-off-by: Vijay Krishnamoorthy <adivarah@codeaurora.org>