staging:r8188eu: remove unused WIFI_MP_*STATE and WIFI_MP_CTX* definitions

fw_state member of struct mlme_priv never obtain WIFI_MP_STATE value,
so code only for (fw_state == WIFI_MP_STATE) is dead.
Remove it, WIFI_MP_*STATE and WIFI_MP_CTX* definitions.

Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>