drm/amdkfd: add missing void argument to function kgd2kfd_init

Function kgd2kfd_init is missing a void argument, add it
to clean up the non-ANSI function declaration.

Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>