x86: Add /sys/firmware/memmap

[Bernhard Walle]

This patch series adds a new interface /sys/firmware/memmap
to export the BIOS (Firmware) provided memory map via sysfs
for usage with kexec.

While the first patch adds the generic interface, the second
patch implements that interface for E820 on x86. EFI is on the TODO
list, and other architectures can be added later.


Signed-off-by: Bernhard Walle <bwalle at suse.de>