Enable amdgpu support for SI parts

configname: CONFIG_DRM_AMDGPU_SI

Linux Kernel Configuration
└─>Device Drivers
└─>Graphics support
└─>Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)
└─>Enable amdgpu support for SI parts
In linux kernel since version 3.10 (release Date: 2013-06-30)
Choose this option if you want to enable support
for SI (Southern Islands) asics.

SI (Southern Islands) are first generation GCN GPUs,
supported by both drivers: radeon (old) and amdgpu (new).
By default, SI dedicated GPUs are supported by amdgpu.

Use module options to override this:
To use radeon for SI,
radeon.si_support=1 amdgpu.si_support=0