ARM: dts: rockchip: remove always-on and boot-on from vcc_sd for px3-evb

Please don't add these for vcc_sd, and mmc-core/driver will control
it. Otherwise, it will waste energy even without sdmmc in slot.

Moreover, it will causes a bug:
If we insert/remove sd card, we could see
[9.337271] mmc0: new ultra high speed SDR25 SDHC card at address 0007
[9.345144] mmcblk0: mmc0:0007 SD32G 29.3 GiB

This is okay for normal sd insert/remove test, but when I debug some
issues for sdmmc, I did unbind/bind test. And there is a interesting
phenomenon when we bind the driver again:
[58.314069] mmc0: new high speed SDHC card at address 0007
[58.320282] mmcblk0: mmc0:0007 SD32G 29.3 GiB

So the sd card could just support high speed without power cycle
since the vcc_sd is always on, which makes the sd card fail to
reinit its internal ocr mask.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>