drm/amd/display: Deallocate DML memory if allocation fails

In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Deallocate DML memory if allocation fails

[Why]

When DC state create DML memory allocation fails, memory is not

deallocated subsequently, resulting in uninitialized structure

that is not NULL.

[How]

Deallocate memory if DML memory allocation fails.