Docker: Fixed build args for rocm GFX target

This was an issue hwen building against a GFX target that doesn't match
the curent one (e.g. in Docker without exposing the GPU).

See leejet#843

Author: fkleon

Dockerfile.rocm

@@ -23,7 +23,9 @@ RUN mkdir -p build \
     -DSD_HIPBLAS=ON \
     -DCMAKE_BUILD_TYPE=Release \
     -DGPU_TARGETS=$GFX_NAME \
+    -DAMDGPU_TARGETS=$GFX_NAME \
     -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON \
+    -DCMAKE_POSITION_INDEPENDENT_CODE=ON \
   && cmake --build . --config Release
 
 FROM rocm/dev-ubuntu-${UBUNTU_VERSION}:${ROCM_VERSION}-complete AS runtime