staging: r8188eu: write only path a registers in rtw_dbg_port

Commit 3b011b09 ("staging: r8188eu: limit rf register writes to
path a") limited the rtw_wx_write_rf function to write only rf registers
for path a.

The private ioctl 0x0B invokes the rtw_dbg_port function. This ioctl
can also be used for writing rf registers. We should limit these register
writes to rf path a as well.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220212161737.381841-3-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/os_dep/ioctl_linux.c

@@ -3621,7 +3621,11 @@ static int rtw_dbg_port(struct net_device *dev,
 		DBG_88E("read RF_reg path(0x%02x), offset(0x%x), value(0x%08x)\n", minor_cmd, arg, rtl8188e_PHY_QueryRFReg(padapter, minor_cmd, arg, 0xffffffff));
 		break;
 	case 0x75:/* write_rf */
-		rtl8188e_PHY_SetRFReg(padapter, minor_cmd, arg, 0xffffffff, extra_arg);
+		if (minor_cmd != RF_PATH_A) {
+			ret = -EINVAL;
+			break;
+		}
+		rtl8188e_PHY_SetRFReg(padapter, RF_PATH_A, arg, 0xffffffff, extra_arg);
 		DBG_88E("write RF_reg path(0x%02x), offset(0x%x), value(0x%08x)\n", minor_cmd, arg, rtl8188e_PHY_QueryRFReg(padapter, minor_cmd, arg, 0xffffffff));
 		break;