util: Fix warning in u_cpu_detect on non-x86

regs is only set and used on x86; on other platforms (like ARM), this
code causes a trivial warning, solved by moving the regs declaration to
the architecture-dependent usage.
Reviewed-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

src/util/u_cpu_detect.c

@@ -370,14 +370,14 @@ check_os_arm_support(void)
 static void
 get_cpu_topology(void)
 {
-   uint32_t regs[4];
-
    /* Default. This is correct if L3 is not present or there is only one. */
    util_cpu_caps.cores_per_L3 = util_cpu_caps.nr_cpus;
 
 #if defined(PIPE_ARCH_X86) || defined(PIPE_ARCH_X86_64)
    /* AMD Zen */
    if (util_cpu_caps.x86_cpu_type == 0x17) {
+      uint32_t regs[4];
+
       /* Query the L3 cache topology information. */
       cpuid_count(0x8000001D, 3, regs);
       unsigned cache_level = (regs[0] >> 5) & 0x7;