ARM: dts: imx7s-warp: Pass 'no-1-8-v' property to the eMMC

Currently the following eMMC error is seen:

mmc1: mmc_select_hs200 failed, error -74
mmc1: new MMC card at address 0001
mmcblk1: mmc1:0001 V10008 7.05 GiB
mmcblk1boot0: mmc1:0001 V10008 partition 1 4.00 MiB
mmcblk1boot1: mmc1:0001 V10008 partition 2 4.00 MiB
mmcblk1rpmb: mmc1:0001 V10008 partition 3 4.00 MiB

On imx7s-warp the eMMC VCCQ is fixed at 3.15V, so pass the 'no-1-8-v'
property to properly describe that 1.8V operation is not possible.

With this change HS200 error is gone and another benefit is that the
card can operate in DDR52 mode now:

mmc1: new DDR MMC card at address 0001
mmcblk1: mmc1:0001 V10008 7.05 GiB
mmcblk1boot0: mmc1:0001 V10008 partition 1 4.00 MiB
mmcblk1boot1: mmc1:0001 V10008 partition 2 4.00 MiB
mmcblk1rpmb: mmc1:0001 V10008 partition 3 4.00 MiB

Suggested-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>