When we encounter an error while initting the microcode driver on a CPU,
we must undo the previously added sysfs group.

Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>
Acked-by: NAndreas Herrmann <Andreas.Herrmann3@amd.com>