staging: r8188eu: remove unused hal_xmit_handler define

hal_xmit_handler is not used by the r8188eu driver. Remove it.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Acked-by: Pavel Skripkin <paskripkin@gmail.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20230109212852.75612-8-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/include/rtl8188e_xmit.h

@@ -134,7 +134,6 @@ void rtl8188e_fill_fake_txdesc(struct adapter *padapter, u8 *pDesc,
 s32 rtl8188eu_hal_xmit(struct adapter *padapter, struct xmit_frame *frame);
 s32 rtl8188eu_mgnt_xmit(struct adapter *padapter, struct xmit_frame *frame);
 s32 rtl8188eu_xmit_buf_handler(struct adapter *padapter);
-#define hal_xmit_handler rtl8188eu_xmit_buf_handler
 void rtl8188eu_xmit_tasklet(unsigned long priv);
 bool rtl8188eu_xmitframe_complete(struct adapter *padapter,
 				 struct xmit_priv *pxmitpriv);