UART-NOZEN made optional component.

UART-NOZEN made optional component.

Please, if you add component or application, and
you are not sure, if it works for all other users,
be so polite and made it optional.

Look at this patch, how it should look like.
  CONFIG_UART_NOZEN=y

If you want to use it, add it into your config.omk

If it is specific/required for given board, add it
into
  sysless-lpc21xx/board/xxx/config.xxx
which should be used as base for config.target

Please, register into Sysless conference on Pandora
and try to keep things usable for others.

  http://pandora.idnes.cz/conference/sysless/

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>