staging/crystalhd: assign PTR_ERR at fail cases to rc in chd_dec_init_chdev

the rc assignment to PTR_ERR at fail cases of class_create and device_create are missed out,
return proper error rather than returning -ENODEV.

Signed-off-by: Devendra Naga <develkernel412222@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>