[Blackfin] arch: Encourage users to use the spidev character driver: Provide platform support

 - Enable kernel generic spidev driver for blackfin SPI ADC
 - spi_adc driver, document and test sample not synced

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/mach-bf548/boards/ezkit.c b/arch/blackfin/mach-bf548/boards/ezkit.c
index 638da39..d5330d4 100644
--- a/arch/blackfin/mach-bf548/boards/ezkit.c
+++ b/arch/blackfin/mach-bf548/boards/ezkit.c
@@ -420,6 +420,13 @@
 };
 #endif
 
+#if defined(CONFIG_SPI_SPIDEV) || defined(CONFIG_SPI_SPIDEV_MODULE)
+static struct bfin5xx_spi_chip spidev_chip_info = {
+	.enable_dma = 0,
+	.bits_per_word = 8,
+};
+#endif
+
 static struct spi_board_info bf54x_spi_board_info[] __initdata = {
 #if defined(CONFIG_MTD_M25P80) \
 	|| defined(CONFIG_MTD_M25P80_MODULE)
@@ -445,6 +452,15 @@
 	.controller_data = &spi_ad7877_chip_info,
 },
 #endif
+#if defined(CONFIG_SPI_SPIDEV) || defined(CONFIG_SPI_SPIDEV_MODULE)
+	{
+		.modalias = "spidev",
+		.max_speed_hz = 3125000,     /* max spi clock (SCK) speed in HZ */
+		.bus_num = 0,
+		.chip_select = 1,
+		.controller_data = &spidev_chip_info,
+	},
+#endif
 };
 
 /* SPI (0) */