KVM: arm64: Use the bitmap API to allocate bitmaps

Use bitmap_zalloc()/bitmap_free() instead of hand-writing them.

It is less verbose and it improves the semantic.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/3c5043731db4d3635383e9326bc7e98e25de3288.1681854412.git.christophe.jaillet@wanadoo.fr

arch/arm64/kvm/vmid.c

@@ -182,8 +182,7 @@ int __init kvm_arm_vmid_alloc_init(void)
 	 */
 	WARN_ON(NUM_USER_VMIDS - 1 <= num_possible_cpus());
 	atomic64_set(&vmid_generation, VMID_FIRST_VERSION);
-	vmid_map = kcalloc(BITS_TO_LONGS(NUM_USER_VMIDS),
-			   sizeof(*vmid_map), GFP_KERNEL);
+	vmid_map = bitmap_zalloc(NUM_USER_VMIDS, GFP_KERNEL);
 	if (!vmid_map)
 		return -ENOMEM;
 
@@ -192,5 +191,5 @@ int __init kvm_arm_vmid_alloc_init(void)
 
 void __init kvm_arm_vmid_alloc_free(void)
 {
-	kfree(vmid_map);
+	bitmap_free(vmid_map);
 }