Description: drm/amd/display: Fix potential null pointer dereference in dc_dmub_srv
References:
Notes:
 carnil> Introduced in 028bac583449 ("drm/amd/display: decouple dmcub execution to
 carnil> reduce lock granularity")
 carnil> 65138eb72e1f ("drm/amd/display: Add DCN35 DMUB"). Vulnerable versions: 6.7-rc1.
Bugs:
upstream: released (6.8-rc6) [d2b48f340d9e4a8fbeb1cdc84cd8da6ad143a907]
6.7-upstream-stable: released (6.7.7) [351080ba3414c96afff0f1338b4aeb2983195b80]
6.6-upstream-stable: N/A "Vulnerable code not present"
6.1-upstream-stable: N/A "Vulnerable code not present"
5.10-upstream-stable: N/A "Vulnerable code not present"
4.19-upstream-stable: N/A "Vulnerable code not present"
sid: released (6.7.7-1)
6.1-bookworm-security: N/A "Vulnerable code not present"
5.10-bullseye-security: N/A "Vulnerable code not present"
4.19-buster-security: N/A "Vulnerable code not present"