add alpha sample

target/alpha/kernel/dec-alphastation-m3

@@ -0,0 +1,5 @@
+CONFIG_ALPHA=y
+CONFIG_ALPHA_AVANTI_CH=y
+CONFIG_ISA=y
+CONFIG_ISA_DMA_API=y
+CONFIG_ALPHA_SRM=y

target/alpha/systems/dec-alphastation-m3

@@ -0,0 +1,8 @@
+config ADK_TARGET_SYSTEM_DEC_ALPHASTATION_M3
+	bool "Digital Alphastation 250 4/266 (M3)"
+	select ADK_TARGET_CPU_ALPHA_EV4
+	select ADK_TARGET_KERNEL_WITH_COMPRESSION
+	help
+	  Support for DEC Alphastation. See:
+	  https://en.wikipedia.org/wiki/AlphaStation
+