mkelfimage: remove

It's not been needed for years, is definitely not needed now
that cbfstool parses bzImages, and its presence keeps confusing
people.

Also, rewrite history. We never mentioned mkelfimage in the
documentation. Never, ever, ever.

Change-Id: Id96a57906ba6a423b06a8f4140d2efde6f280d55
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-on: http://review.coreboot.org/7021
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <gaumless@gmail.com>
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

documentation/CorebootBuildingGuide.tex

@@ -1353,21 +1353,8 @@ utilities suite. Get it at
 \subsection {Booting Payloads}
 coreboot can load a payload binary from a Flash device or IDE. This
 payload can be a boot loader, like FILO or Etherboot, a kernel image, or
-any other static ELF binary.
-
-To create a Linux kernel image, that is bootable in coreboot, you have
-to use mkelfImage. The command line I used, looks like follows:
-
-\begin{verbatim}
-    objdir/sbin/mkelfImage t bzImagei386 kernel /boot/vmlinuz \
-             commandline="console=ttyS0,115200 root=/dev/hda3" \
-             initrd=/boot/initrd output vmlinuz.elf
-\end{verbatim}
-
-
-This will create the file \texttt{vmlinuz.elf} from a distribution
-kernel, console redirected to the serial port and using an initial
-ramdisk.
+any other static ELF binary. If you specify a bzImage as the payload,
+the cbfs utility will figure out how to create a coreboot payload from it.
 
 \subsection{Kernel on dhcp/tftp}