staging: rtl8188eu: Remove function rtw_hal_dm_deinit()

rtw_hal_dm_deinit() calls rtl8188e_deinit_dm_priv() using funtion pointer.
rtl8188e_deinit_dm_priv() has empty defination, so we can remove
rtw_hal_dm_deinit() and later rtl8188e_deinit_dm_priv() also will be
removed.

Signed-off-by: navin patidar <navin.patidar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>