ARM: dts: lpc32xx: Remove unused and undocumented 'pnx,timeout'

'pnx,timeout' is unused, undocumented and 'pnx' is not a vendor prefix,
so let's remove it.

Acked-by: Vladimir Zapolskiy <vz@mleia.com>
Cc: Sylvain Lemieux <slemieux.tyco@gmail.com>
Link: https://lore.kernel.org/r/20201210175238.2721550-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>