drm/amd: Fix logic error in sienna_cichlid_update_pcie_parameters()

While aligning SMU11 with SMU13 implementation an assumption was made that
`dpm_context->dpm_tables.pcie_table` was populated in dpm table initialization
like in SMU13 but it isn't.

So restore some of the original logic and instead just check for
amdgpu_device_pcie_dynamic_switching_supported() to decide whether to hardcode
values; erring on the side of performance.

Cc: stable@vger.kernel.org # 6.1+
Reported-and-tested-by: Umio Yasuno <coelacanth_dream@protonmail.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/1447#note_2101382
Fixes: e701156c

 ("drm/amd: Align SMU11 SMU_MSG_OverridePcieParameters implementation with SMU13")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>