Ath6kl: partially completed ath6kl_init_hw_start.

Driver reaches the firmware mode is set state before failing.

* Add the following functions/macros for BMI layer:
    o ath6kl_bmi_read
    o ath6kl_bmi_write
    o ath6kl_bmi_write_hi32
    o ath6kl_bmi_read_hi32;
* Initialized some softc variables in ath6kl_core_create;
* Add helper function ath6kl_get_hi_item_addr;
* Partially and the following function ath6kl_core_init:
    o ath6kl_configure_target
    o ath6kl_configure_target;