msm: camera: isp: clearing isp context entries for rdi_only_context

Due to stale entry of rdi_only_context, the initial state of non-rdi
state machine is wrongly selected if
1. The non-rdi session comes after rdi session and
2. non-rdi session acquires same context-id

Change-Id: Ib5fca57158ff08a610ef6854dee020b94f52b391
Signed-off-by: Alok Pandey <akumarpa@codeaurora.org>