x86/resctrl: Slightly clean-up mbm_config_show()

x86/resctrl: Slightly clean-up mbm_config_show()

'mon_info' is already zeroed in the list_for_each_entry() loop below.  There
is no need to explicitly initialize it here. It just wastes some space and
cycles.

Remove this un-needed code.

On a x86_64, with allmodconfig:

  Before:
  ======
     text	   data	    bss	    dec	    hex	filename
    74967	   5103	   1880	  81950	  1401e	arch/x86/kernel/cpu/resctrl/rdtgroup.o

  After:
  =====
     text	   data	    bss	    dec	    hex	filename
    74903	   5103	   1880	  81886	  13fde	arch/x86/kernel/cpu/resctrl/rdtgroup.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lore.kernel.org/r/b2ebc809c8b6c6440d17b12ccf7c2d29aaafd488.1720868538.git.christophe.jaillet@wanadoo.fr