spi: spi-uclass: Read chipselect and restrict capabilities

Read chipselect properties from DT which are populated using 'reg'
property and save it in plat->cs[] array for later use.

Also read multi chipselect capability which is used for
parallel-memories and return errors if they are passed on using DT but
driver is not capable of handling it.

Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@amd.com>
Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
diff --git a/drivers/spi/rk_spi.c b/drivers/spi/rk_spi.c
index 4571dc9..2c3d70b 100644
--- a/drivers/spi/rk_spi.c
+++ b/drivers/spi/rk_spi.c
@@ -444,7 +444,7 @@
 
 	/* Assert CS before transfer */
 	if (flags & SPI_XFER_BEGIN)
-		spi_cs_activate(dev, slave_plat->cs);
+		spi_cs_activate(dev, slave_plat->cs[0]);
 
 	/*
 	 * To ensure fast loading of firmware images (e.g. full U-Boot
@@ -507,7 +507,7 @@
 
 	/* Deassert CS after transfer */
 	if (flags & SPI_XFER_END)
-		spi_cs_deactivate(dev, slave_plat->cs);
+		spi_cs_deactivate(dev, slave_plat->cs[0]);
 
 	rkspi_enable_chip(regs, false);
 	if (!out)