staging: prism2sta: Replace memcpy with ether_add_copy

Replace memcpy() with ether_addr_copy() since addresses are __aligned(2).
The 2 structures are aligned to u16 as showed below:

typedef struct hfa384x_authenticateStation_data {
u8 address[ETH_ALEN];                           /* 0    6 */
u16 status;                                     /* 6    2 */
u16 algorithm;                                  /* 8    2 */
} __packed hfa384x_authenticateStation_data_t;

Total size: 10

typedef struct hfa384x_AuthRequest {
u8 sta_addr[ETH_ALEN];                          /* 0    6 */
u16 algorithm;                                  /* 6    2 */
} __packed hfa384x_AuthReq_t;
Total size: 8

Signed-off-by: Ioana Ciornei <ciorneiioana@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>