staging: wilc1000: change void pointer type to real type

This patch changes the void pointer member of the tstrHostIFmsg to the
real data type because the void pointer type is ambiguous and not
readable.

Signed-off-by: Johnny Kim <johnny.kim@atmel.com>
Signed-off-by: Tony Cho <tony.cho@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>