mce: Add a x86_mcinfo_reserve() function, to reserve space from mc_info.

mce: Add a x86_mcinfo_reserve() function, to reserve space from mc_info.

With this method, we don't need to collect bank and globalinformation
to a local variable and do x86_mcinfo_add() to copy that information
to mc_info.  This avoid copy and also we can be aware earlier if there
is enough space in the mc_info.

Also extract function that get global/bank information to seperated
function mca_init_bank/mca_init_global.

It's meaningless to get the current information in mce context, keep
it here but should be removed in future.

Also a flag added to mc_info, to indicate some information is lost due
to OOM.

Signed-off-by: Jiang, Yunhong <yunhong.jiang@intel.com>