drm/amdkfd: Fix improper NULL termination of queue restore SMI event string

drm/amdkfd: Fix improper NULL termination of queue restore SMI event string

Pass character "0" rather than NULL terminator to properly format
queue restoration SMI events. Currently, the NULL terminator precedes
the newline character that is intended to delineate separate events
in the SMI event buffer, which can break userspace parsers.

Signed-off-by: Brian Kocoloski <brian.kocoloski@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>