arm: rmobile: Add SILK board support

SILK is an entry level development board based on R-Car E2 SoC (R8A7794)

This commit supports the following peripherals:
- SCIF, I2C, Ethernet, QSPI, MMC, USB Host

Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Reviewed-by: Tom Rini <trini@ti.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/board/renesas/silk/Kconfig b/board/renesas/silk/Kconfig
new file mode 100644
index 0000000..07aee0e
--- /dev/null
+++ b/board/renesas/silk/Kconfig
@@ -0,0 +1,12 @@
+if TARGET_SILK
+
+config SYS_BOARD
+	default "silk"
+
+config SYS_VENDOR
+	default "renesas"
+
+config SYS_CONFIG_NAME
+	default "silk"
+
+endif