drm/amd/pm: Remove redundant check condition

V3:
[Why]:
  Since ASICs using smu v13_0_2 have called smu
.suspend before calling amdgpu_pm_sysfs_fini,
pm.dpm_enabled was already set to 0 when smu
.suspend was called. This makes it impossible
to delete all pm sys nodes.

[How]:
  Since all functions in amdgpu_pm_sysfs_fini
have their own condition checks, so the first
conditional check in amdgpu_pm_sysfs_fini can
be removed.

Signed-off-by: YiPeng Chai <YiPeng.Chai@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>