diag: Proper update of non real time mode during mdlog session

Real time mode is updated to peripherals when mdlog session is
started due to improper check. Check has been corrected to update
non real time mode when needed.

Change-Id: I86b9eb34bbeb1a09fa6b52efa39470e476fe7e6d
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>