amd/amdkfd: remove svms declaration to avoid werror

svm_range_list svms declaration removed to avoid werror when
CONFIG_HSA_AMD_SVM is not enabled.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>