drm/amd/display: increase max link count and fix link->enc NULL pointer access

[why]
1.) dc->links[MAX_LINKS] array size smaller than actual requested.
max_connector + max_dpia + 4 virtual = 14.
increase from 12 to 14.

2.) hw_init() access null LINK_ENC for dpia non display_endpoint.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Reviewed-by: Chris Park <chris.park@amd.com>
Signed-off-by: Charlene Liu <Charlene.Liu@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit d7f5a61)
Cc: stable@vger.kernel.org

Author: charliu-AMDENG

drivers/gpu/drm/amd/display/dc/hwss/dcn401/dcn401_hwseq.c

@@ -200,6 +200,9 @@ void dcn401_init_hw(struct dc *dc)
 		 */
 		struct dc_link *link = dc->links[i];
 
+		if (link->ep_type != DISPLAY_ENDPOINT_PHY)
+			continue;
+
 		link->link_enc->funcs->hw_init(link->link_enc);
 
 		/* Check for enabled DIG to identify enabled display */

drivers/gpu/drm/amd/display/dc/inc/hw/hw_shared.h

@@ -44,7 +44,13 @@
  */
 #define MAX_PIPES 6
 #define MAX_PHANTOM_PIPES (MAX_PIPES / 2)
-#define MAX_LINKS (MAX_PIPES * 2 +2)
+
+#define MAX_DPIA 6
+#define MAX_CONNECTOR 6
+#define MAX_VIRTUAL_LINKS 4
+
+#define MAX_LINKS (MAX_DPIA + MAX_CONNECTOR + MAX_VIRTUAL_LINKS)
+
 #define MAX_DIG_LINK_ENCODERS 7
 #define MAX_DWB_PIPES	1
 #define MAX_HPO_DP2_ENCODERS	4