drm/amdgpu: fix parameter error of RREG32_PCIE() in amdgpu_regs_pcie

the register offset isn't needed division by 4 to pass RREG32_PCIE()

Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org