crypto: vmx - Make p8_init and p8_exit static

Fix sparse warnings:

drivers/crypto/vmx/vmx.c:44:12: warning:
 symbol 'p8_init' was not declared. Should it be static?
drivers/crypto/vmx/vmx.c:70:13: warning:
 symbol 'p8_exit' was not declared. Should it be static?

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>