drm/radeon: Don't increment pipe_id in kgd_init_pipeline

This patch fixes the behavior of kgd_init_pipeline in that this function
shouldn't automatically increase the pipe_id argument by 1 right at the start
of the function.

This is because the first_pipe value might not be always 1, and because a
proper interface function should not hide this info inside its implementation.
In other words, the calling function should provide the real pipe_id and not
count on kgd_init_pipeline to "fix" it.

Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>