wifi: rtw88: remove unused rtw_pci_get_tx_desc function

clang with W=1 reports
drivers/net/wireless/realtek/rtw88/pci.c:92:21: error:
  unused function 'rtw_pci_get_tx_desc' [-Werror,-Wunused-function]
static inline void *rtw_pci_get_tx_desc(struct rtw_pci_tx_ring *tx_ring, u8 idx)
                    ^
This function is not used, so remove it.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230320233448.1729899-1-trix@redhat.com

drivers/net/wireless/realtek/rtw88/pci.c

@@ -89,13 +89,6 @@ static void rtw_pci_write32(struct rtw_dev *rtwdev, u32 addr, u32 val)
 	writel(val, rtwpci->mmap + addr);
 }
 
-static inline void *rtw_pci_get_tx_desc(struct rtw_pci_tx_ring *tx_ring, u8 idx)
-{
-	int offset = tx_ring->r.desc_size * idx;
-
-	return tx_ring->r.head + offset;
-}
-
 static void rtw_pci_free_tx_ring_skbs(struct rtw_dev *rtwdev,
 				      struct rtw_pci_tx_ring *tx_ring)
 {