Rename SM4-CNTR references to SM4-CTR

Except for IMB_CIPHER_SM4_CNTR cipher mode enum,
which remains as it is, to avoid API breakage on frameworks like DPDK that
are already using this enum (IMB_CIPHER_SM4_CTR is also defined, though).

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>