intel/lynxpoint: Make inclusion of Intel ME optional

intel/lynxpoint: Make inclusion of Intel ME optional

Current build configuration always wants to include an Intel Management Engine
(ME) firmware (`me.bin`) on Intel Lynx Point systems.  However, we can have a
working coreboot without it, as long as the factory delivered ME firmware is
kept untouched in the flash ROM. So let the user decide if a ME firmware will
be included in the build by introducing the Kconfig option `HAVE_ME_BIN`.

The same was done in commit 99fd30e4 (sandybridge: Make inclusion of me.bin
optional) [1] for Intel Sandy Bridge (BD82x6x).

[1] http://review.coreboot.org/3522

Change-Id: I7c6048fd0f56288769ad90acbfb67b908ac8d824
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: http://review.coreboot.org/6047
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>