Add generic: Artix7 gtp depends on rx_byte_is_aligned
This merge request replaces merge request "Revert gtp_bitslide.vhd SHA-1: c9cc5ca back to version SHA-1: 8a4c319".
This issue is now solved by introducing a generic "g_use_rx_byte_is_aligned" (default = false). In case of Artix7 GTP the genreic is set true in order to use signal rx_byte_is_aligned instead of rx_comma_det + counter.