staging: wilc1000: host_infterface.h: remove unused enum tenuWILC_StaFlag

This patch removes unused enum tenuWILC_StaFlag from the
host_interface.h.

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