disp: msm: sde: handle cont-splash & check only rm reserve

On the first commit, cont splash flag is still enabled on
encoder, but connector is not yet attached. When a check-only
rm reservation is made, it does not get released due to
cont-splash check. If cont-splash is enabled, rm should
not check for connector, but directly release rsvp_nxt.

Change-Id: I79be3c1bb20b74ce4a95786c90f3accfb587d7f2
Signed-off-by: Nilaan Gunabalachandran <ngunabal@codeaurora.org>