staging: speakup: cleanup spk_var_header_by_name()

There is a confusing while loop here and I have re-written it in
canonical for loop format.  Also I reversed the NULL check on "name" and
pulled everything in one tab stop.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>