char drivers: RAM oops/panic logger

Ramoops, like mtdoops, can log oops/panic information but in RAM.  It can
be used with persistent RAM for systems without flash support.  In
addition, for this systems, with this driver, it's no more needed add to
the kernel the mtd subsystem with advantage in footprint.

It can be used in a very easy way with persistent RAM for systems without
flash support.  For these systems, with this driver, it is no longer
required to cinlude mtd subsystem with an advantage in footprint.  In
addition, you can save flash space and store this information only in RAM.

Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
Cc: Simon Kagstrom <simon.kagstrom@netinsight.net>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc; Anders Grafstrom <anders.grafstrom@netinsight.net>
Cc: Yuasa Yoichi <yuasa@linux-mips.org>
Cc: Jamie Lokier <jamie@shareable.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>