crypto: cavium - Make some functions static

Fix sparse warnings:

drivers/crypto/cavium/cpt/cptvf_reqmanager.c:226:5: warning: symbol 'send_cpt_command' was not declared. Should it be static?
drivers/crypto/cavium/cpt/cptvf_reqmanager.c:273:6: warning: symbol 'do_request_cleanup' was not declared. Should it be static?
drivers/crypto/cavium/cpt/cptvf_reqmanager.c:319:6: warning: symbol 'do_post_process' was not declared. Should it be static?

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