drm/amd/powerplay: fix thermal interrupts on vega10

a bug in programming thermal interrupt register masks out
interrupts and driver cannot receive interrupts. Setting
0 to mask bits will fix it.

Signed-off-by: Eric Huang <JinHuiEric.Huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>