xen/cache-col: address MISRA C Rule 5.3

MISRA C:2012 Rule 5.3 states as following: An identifier declared in an
inner scope shall not hide an identifier declared in an outer scope.

Inside the 'if' block, the inner 'i' shadows the outer 'i'.
Reuse the outer variable and remove the inner declaration to fix that.

No functional change.

Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@epam.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/common/llc-coloring.c

@@ -193,8 +193,6 @@ void __init llc_coloring_init(void)
 
     if ( !xen_num_colors )
     {
-        unsigned int i;
-
         xen_num_colors = MIN(XEN_DEFAULT_NUM_COLORS, max_nr_colors);
 
         printk(XENLOG_WARNING