Fix memory wipe with recent kernel

Originally created by @intrigeri on #6460 (Redmine)

See Shutdown stopped working in nightly experimental? and Fix sdmem on Intel graphic hardware, please review threads on tails-dev.

Not better with the following (one change at a time) attempts:

• Linux 3.12 (3.12-1~exp1) from Debian experimental
• Linux 3.12.3 (3.12.3-1~exp1) from Debian experimental
• Linux 3.12.6 (3.12.6-1) from Debian unstable
• Linux 3.13-rc6 (3.13~rc6-1~exp1) from Debian experimental
• kexec-tools 2.0.4-1
• initramfs-tools 0.114
• removing --reset-vga from the tails-kexec initscript

This might be the same problem as:

• reported by Dave Young on LKML
• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=731313
• https://bugzilla.kernel.org/show_bug.cgi?id=66171
• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=731039

Something that could be worth giving a try is booting with KMS disabled. If this works, then we may narrow it down to a graphics driver issue.

Feature Branch: feature/disable-mei

Related issues

• Related to #5948
• Related to #6467 (closed)
• Related to #6584 (closed)