drm/amd/amdgpu: Initialize swnode for ISP MFD device

drm/amd/amdgpu: Initialize swnode for ISP MFD device

Create amd_isp_capture MFD device with swnode initialized to
isp specific software_node part of fwnode graph in amd_isp4
x86/platform driver. The isp driver use this swnode handle
to retrieve the critical properties (data-lanes, mipi phyid,
link-frequencies etc.) required for camera to work on AMD ISP4
based targets.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Pratap Nirujogi <pratap.nirujogi@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>