staging: r8188eu: remove unused function prototype

There's no rtw_write_scsi function in this driver. Remove its prototype.
Acked-by: Michael Straube <straube.linux@gmail.com>
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210908085747.32254-2-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/include/rtw_io.h

@@ -298,8 +298,6 @@ void _rtw_write_port_cancel(struct adapter *adapter);
 	_rtw_write_port_and_wait((adapter), (addr), (cnt), (mem), (timeout_ms))
 #define rtw_write_port_cancel(adapter) _rtw_write_port_cancel((adapter))
 
-void rtw_write_scsi(struct adapter *adapter, u32 cnt, u8 *pmem);
-
 /* ioreq */
 void ioreq_read8(struct adapter *adapter, u32 addr, u8 *pval);
 void ioreq_read16(struct adapter *adapter, u32 addr, u16 *pval);