x86 boot : export boot_params via debugfs for debugging

This patch export the boot parameters via debugfs for debugging.

The files added are as follow:

boot_params/data    :  binary file for struct boot_params
boot_params/version :  boot protocol version

This patch is based on 2.6.24-rc5-mm1 and has been tested on i386 and
x86_64 platform.

This patch is based on the Peter Anvin's proposal.

Signed-off-by: Huang Ying <ying.huang@intel.com>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>