drm/amdgpu/gfx12: correct cleanup of 'me' field with gfx_v12_0_me_fini()

In gfx_v12_0_cp_gfx_load_me_microcode_rs64(), gfx_v12_0_pfp_fini() is
incorrectly used to free 'me' field of 'gfx', since gfx_v12_0_pfp_fini()
can only release 'pfp' field of 'gfx'. The release function of 'me' field
should be gfx_v12_0_me_fini().

Fixes: 52cb80c1 ("drm/amdgpu: Add gfx v12_0 ip block support (v6)")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>