The current implementation is hardcoded to enable ME1/PIPE0 interrupts
only.

This patch allows amdgpu to enable interrupts for any pipe of ME1.

v2: added gfx9 support
v3: use soc15_grbm_select for gfx9
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>