arm: rmobile: Add Porter board support

Porter is an entry level development board based on R-Car M2 SoC (R8A7791)

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

Signed-off-by: Vladimir Barinov <vladimir.barinov@cogentembedded.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/arch/arm/cpu/armv7/rmobile/Kconfig b/arch/arm/cpu/armv7/rmobile/Kconfig
index 3586650..2b333a3 100644
--- a/arch/arm/cpu/armv7/rmobile/Kconfig
+++ b/arch/arm/cpu/armv7/rmobile/Kconfig
@@ -24,6 +24,9 @@
 config TARGET_SILK
 	bool "Silk board"
 
+config TARGET_PORTER
+	bool "Porter board"
+
 endchoice
 
 config SYS_SOC
@@ -31,7 +34,7 @@
 
 config RMOBILE_EXTRAM_BOOT
 	bool "Enable boot from RAM"
-	depends on TARGET_ALT || TARGET_KOELSCH || TARGET_LAGER || TARGET_SILK
+	depends on TARGET_ALT || TARGET_KOELSCH || TARGET_LAGER || TARGET_PORTER || TARGET_SILK
 	default n
 
 source "board/atmark-techno/armadillo-800eva/Kconfig"
@@ -41,5 +44,6 @@
 source "board/kmc/kzm9g/Kconfig"
 source "board/renesas/alt/Kconfig"
 source "board/renesas/silk/Kconfig"
+source "board/renesas/porter/Kconfig"
 
 endif