crypto/qat: rename functions for consistency

crypto/qat: rename functions for consistency

Rename fn names to shorten them, i.e.
  qat_crypto_sym_xxx to qat_sym_xxx
  _content_desc_ to _cd_
Renaming symmetric crypto specific with consistent names:
  qat_crypto_set_session_parameters->qat_sym_set_session_parameters
  qat_write_hw_desc_entry()->qat_sym_build_request()
  qat_alg_xxx ->qat_sym_xxx
  qat_sym_xxx_session_yyy()->qat_sym_session_xxx_yyy()
Removed unused prototypes:
  qat_get_inter_state_size()
  qat_pmd_session_mempool_create()
Removed 2 unnecessary extern declarations

Signed-off-by: Fiona Trahe <fiona.trahe@intel.com>