util: fix (re-enable) L3 cache pinning

cores_per_L3 was uninitialized, so it was always disabled.
Remove the variable and do it differently.

Fixes: 11d2db17c5 - util: rework AMD cpu L3 cache affinity code.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10526>

src/util/u_cpu_detect.c

@@ -435,7 +435,6 @@ static void
 get_cpu_topology(void)
 {
    /* Default. This is OK if L3 is not present or there is only one. */
-   util_cpu_caps.cores_per_L3 = util_cpu_caps.nr_cpus;
    util_cpu_caps.num_L3_caches = 1;
 
    memset(util_cpu_caps.cpu_to_L3, 0xff, sizeof(util_cpu_caps.cpu_to_L3));

src/util/u_cpu_detect.h

@@ -97,7 +97,6 @@ struct util_cpu_caps_t {
    unsigned has_avx512vbmi:1;
 
    unsigned num_L3_caches;
-   unsigned cores_per_L3;
    unsigned num_cpu_mask_bits;
 
    uint16_t cpu_to_L3[UTIL_MAX_CPUS];