spi: pl022: remove nonexistent properties from DT binding example

spi: pl022: remove nonexistent properties from DT binding example

The properties "pl022,hierarchy" and "pl022,slave-tx-disable" were
initially proposed till patch V4 [1] but then discarded in V5 [2]
when the patch set was taken over by another developer, as
explained in patch history in [3].
The above properties never landed in mainline code but were then
listed in the binding example by a following commit dc715452e914
("spi: pl022: use generic DMA slave configuration if possible")
and later on they were copy-paste in some board's DT.

Remove the nonexistent properties from the example.
Also remove a spaces-only line at the end of the file.

[1] https://lkml.org/lkml/2012/7/9/421
[2] https://lkml.org/lkml/2012/8/21/427
[3] https://lkml.org/lkml/2012/8/21/436

Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>