crypto: vmx - Source headers are not good kernel-doc candidates

Fixes the following W=1 kernel build warning(s):

 drivers/crypto/vmx/vmx.c:23: warning: expecting prototype for Routines supporting VMX instructions on the Power 8(). Prototype was for p8_init() instead

Cc: "Breno Leitão" <leitao@debian.org>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Paulo Flabiano Smorigo <pfsmorigo@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Henrique Cerri <mhcerri@br.ibm.com>
Cc: linux-crypto@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/vmx/vmx.c

 // SPDX-License-Identifier: GPL-2.0-only
-/**
+/*
  * Routines supporting VMX instructions on the Power 8
  *
  * Copyright (C) 2015 International Business Machines Inc.