drm/amdgpu: Fix memory leak in amdgpu_ras_init()

drm/amdgpu: Fix memory leak in amdgpu_ras_init()

When amdgpu_nbio_ras_sw_init() fails in amdgpu_ras_init(), the function
returns directly without freeing the allocated con structure, leading
to a memory leak.

Fix this by jumping to the release_con label to properly clean up the
allocated memory before returning the error code.

Compile tested only. Issue found using a prototype static analysis tool
and code review.

Fixes: fdc94d3a8c88 ("drm/amdgpu: Rework pcie_bif ras sw_init")
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>