amdkfd: process debug trap ioctl only on a primary context

amdkfd: process debug trap ioctl only on a primary context

Set_debug_trap ioctl should work on a specific kfd_process
even when multiple contexts feature is implemented.

For consistency, this commit allow set_debug_trap ioctl only work on the
primary kfd process of a user space program

Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>