zynq.dtsi: Add a label to the SDHC controller

So that other nodes can refer to this one.
sdhci: Add a quirk to disable write-protect

When a board does not have the WP line wired at all, the card
may be detected as read-only. Add a quick and a device property
to turn of WP detection.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Configuration fixes for zynq-miami

Use u-boot SPL (extra partition for SPL)
Input clock is 32MHz
No feedback clock in QSPI
eth reset is MIO 50
Enable voltage regulator supplies by default
Boot from SD as default
SD WP disable
HDMI chip I2C is connected to PL
Regulator A and B outputs were reversed
QSPI partitioning for 256k erase size
Reduce I2C clock to 100kHz