x86/xen: Remove undefined behavior in setup_features()

1 << 31 is undefined. So switch to 1U << 31.

Fixes: 5ead97c8 ("xen: Core Xen implementation")
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220617103037.57828-1-julien@xen.orgSigned-off-by: Juergen Gross <jgross@suse.com>

drivers/xen/features.c

@@ -42,7 +42,7 @@ void xen_setup_features(void)
 		if (HYPERVISOR_xen_version(XENVER_get_features, &fi) < 0)
 			break;
 		for (j = 0; j < 32; j++)
-			xen_features[i * 32 + j] = !!(fi.submap & 1<<j);
+			xen_features[i * 32 + j] = !!(fi.submap & 1U << j);
 	}
 
 	if (xen_pv_domain()) {