slimbus: Avoid same channel definition, removal in same sequence

Do not add the channel removal request to the remove list
when the client sends it right after the channel definition
without sending reconfigure_now request. Also remove the
channel define request from define list. This avoids
channel definition count being inconsistent, which may
lead to slimbus driver going into wrong state.

Signed-off-by: SathishKumar Mani <smani@codeaurora.org>