pia35x: update default quiet boot parameter

- make default boot non-quiet
- fix variable expansion when quiet is set to an empty string

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
pia35x: don't initialize display during boot

- it's unsure if this is causing problems, we notices some rare hangeups
  after a reboot
- we don't need a display driver in u-boot. It's enough to enable the
  backlight to give the user a quick feedback after turning the device
  on.

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>
ds1374: allow specifying the default WD timeout in board file

Signed-off-by: Björn Krombholz <b.krombholz@pironex.de>