mb/emu/spike-riscv: Move usage instructions into Kconfig help

... and fix them in the process.

The Kconfig help text seems to be a slightly better place for such
documentation than a comment in Kconfig.

Change-Id: I4114e17ad9c486a9de059040b0e2821540c31aad
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/23708
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/mainboard/emulation/spike-riscv/Kconfig

@@ -12,9 +12,6 @@
 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 ## GNU General Public License for more details.
 
-# To execute, do:
-# qemu-system-arm -M vexpress-a9 -m 1024M -nographic -kernel build/coreboot.rom
-
 if BOARD_EMULATION_SPIKE_UCB_RISCV
 
 config BOARD_SPECIFIC_OPTIONS # dummy

src/mainboard/emulation/spike-riscv/Kconfig.name

@@ -1,2 +1,7 @@
 config BOARD_EMULATION_SPIKE_UCB_RISCV
 	bool "SPIKE ucb riscv"
+	help
+	  To run coreboot in spike:
+	  * run "make" as usual
+	  * util/riscvtools/make-spike-elf.sh build/coreboot.{rom,elf}
+	  * spike -m1024 build/coreboot.elf