[ Upstream commit de8341ee3ce7316883e836a2c4e9bf01ab651e0f ] There are no backing hardware registers for ih_soft ring. As a result, don't try to access hardware registers for read and write pointers when processing interrupts on the IH soft ring. Signed-off-by: Mukul Joshi <mukul.joshi@amd.com> Acked-by: Christian König <christian.koenig@amd.com> Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Sasha Levin <sashal@kernel.org>