kconfig: drop intermittend forwarder files

With kconfig understanding wildcards, we don't need
Kconfig files that just include other Kconfig files
anymore.

Change-Id: I7584e675f78fcb4ff1fdb0731e340533c5bc040d
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/9298
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/riscv/Kconfig

@@ -1,3 +1,7 @@
+config ARCH_RISCV
+	bool
+	default n
+
 config ARCH_BOOTBLOCK_RISCV
 	bool
 	default n