x86/mce: set mcinfo_comm.type and .size in x86_mcinfo_reserve()

x86/mce: set mcinfo_comm.type and .size in x86_mcinfo_reserve()

All existing calls to x86_mcinfo_reserve() are followed by statements
that set the size and the type of the reserved space, so move them into
x86_mcinfo_reserve() to simplify the code.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>