x86/resctrl: Remove struct rdt_membw::max_delay

max_delay is used by x86's __get_mem_config_intel() as a local variable.
Remove it, replacing it with a local variable.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20200708163929.2783-3-james.morse@arm.com