Resurrect generic_armv5

But only for unbundled build.
Add it to tapas arch options.

Bug: 8108463
Change-Id: I53cd63c6ab2113fee3992650b561658231ea9921
diff --git a/target/board/generic_armv5/system.prop b/target/board/generic_armv5/system.prop
new file mode 100644
index 0000000..137a0f9
--- /dev/null
+++ b/target/board/generic_armv5/system.prop
@@ -0,0 +1,6 @@
+#
+# system.prop for generic sdk
+#
+
+rild.libpath=/system/lib/libreference-ril.so
+rild.libargs=-d /dev/ttyS0