disp: msm: sde: add enc_id check before decrement avail HW resources

Add changes to commit and decrement only those
hardware resources which are required for the modeset.

Timeline of Commit C1 with CWB modeset:
---> Atomic_check
	Primary encoder has allocated required HW resources.
 	CWB encoder has allocated required HW resources.
---> Atomic_commit
	On primary encoder, connector is seamless hence
	there is no virt_modeset call.
	On CWB encoder, there is virt_mode_set call
	and during commit HW blocks there is unconditional
	decrement for all the HW blocks with rsvp_nxt.

This change ensures hardware blocks are available during
dp display mode validations.

Change-Id: Ifd9439cfc96e727c3093af5f47802c8367775cd7
Signed-off-by: Jayaprakash <jmadiset@codeaurora.org>