drm/amd/display: Fix potential memory leak in DMUB hw_init

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix potential memory leak in DMUB hw_init [Why] On resume we perform DMUB hw_init which allocates memory: dm_resume->dm_dmub_hw_init->dc_dmub_srv_create->kzalloc That results in memory leak in suspend/resume scenarios. [How] Allocate memory for the DC wrapper to DMUB only if it was not allocated before. No need to reallocate it on suspend/resume.