arm64: dts: marvell: armada-3720: drop 'marvell,xenon-emmc' properties

arm64: dts: marvell: armada-3720: drop 'marvell,xenon-emmc' properties

The 'marvell,xenon-emmc' property used in some device trees of Armada 3720
based boards is not documented. Due to this dtbs_check throws warnings:

  .../armada-3720-atlas-v5.dtb: mmc@d8000 (marvell,armada-3700-sdhci): Unevaluated properties are not allowed ('marvell,xenon-emmc' was unexpected)
  .../armada-3720-espressobin-emmc.dtb: mmc@d8000 (marvell,armada-3700-sdhci): Unevaluated properties are not allowed ('marvell,xenon-emmc' was unexpected)

Apart from the warnings, 'git grep' says that the property is used in
device trees only:

  $ git grep -n 'marvell,xenon-emmc'
  arch/arm64/boot/dts/marvell/armada-3720-atlas-v5.dts:85:        marvell,xenon-emmc;
  arch/arm64/boot/dts/marvell/armada-3720-espressobin.dtsi:81:    marvell,xenon-emmc;

Although handling of the property was there in an early version of
the 'sdhci-xenon' driver during the initial submission [1], but that
part has been removed in later versions.

Drop the property from the affected device trees due to the reasons
mentioned above.

No functional changes intended, compile tested only.

Link: https://lore.kernel.org/r/0390e7a05b6163deabb545f93729ea615eeaaee2.1477911954.git-series.gregory.clement@free-electrons.com
Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>