staging: wlan-ng: Fix struct definition's and variable type

le16_to_cpu() accepts argument of type __le16 and cpu_to_le16()
returns an argument of type __le16. This patch fixes:
(a) the type of the variable that end's up getting return from
    cpu_to_le16().
(b) the member types of struct hfa384x_host_scan_request_data,
    struct hfa384x_bytestr32 and struct hfa384x_hscan_result_sub.

The following type mismatch warnings reported by sparse
have been fixed:
warning: incorrect type in assignment (different base types)
warning: cast to restricted __le16

Signed-off-by: Suniel Mahesh <sunil.m@techveda.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>