staging: vt6655: extract index manupulation out of function call

This patch will remove if/else by selecting proper argument before
function call, also index is updated before function call.

Signed-off-by: Matej Dujava <mdujava@kocurkovo.cz>
Link: https://lore.kernel.org/r/1588512552-12297-6-git-send-email-mdujava@kocurkovo.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6655/rxtx.c

@@ -266,7 +266,8 @@ s_uGetDataDuration(
 				return 0;
 		} else {
 			/* First Frag or Mid Frag */
-			uNextPktTime = s_uGetTxRsvTime(pDevice, byPktType, len, wRate, bNeedAck);
+			uNextPktTime = s_uGetTxRsvTime(pDevice, byPktType,
+						       len, wRate, bNeedAck);
 		}
 
 		return pDevice->uSIFS + uAckTime + uNextPktTime;
@@ -283,8 +284,8 @@ s_uGetDataDuration(
 				return 0;
 		} else {
 			/* First Frag or Mid Frag */
-			uNextPktTime = s_uGetTxRsvTime(pDevice, byPktType, len,
-						       wRate, bNeedAck);
+			uNextPktTime = s_uGetTxRsvTime(pDevice, byPktType,
+						       len, wRate, bNeedAck);
 		}
 
 		return pDevice->uSIFS + uAckTime + uNextPktTime;
@@ -307,17 +308,15 @@ s_uGetDataDuration(
 			else if (wRate > RATE_54M)
 				wRate = RATE_54M;
 
-			if (byFBOption == AUTO_FB_0) {
-				uNextPktTime = s_uGetTxRsvTime(pDevice,
-							       byPktType, len,
-							       wFB_Opt0[FB_RATE0][wRate - RATE_18M],
-							       bNeedAck);
-			} else {
-				uNextPktTime = s_uGetTxRsvTime(pDevice,
-							       byPktType, len,
-							       wFB_Opt1[FB_RATE0][wRate - RATE_18M],
-							       bNeedAck);
-			}
+			wRate -= RATE_18M;
+
+			if (byFBOption == AUTO_FB_0)
+				wRate = wFB_Opt0[FB_RATE0][wRate];
+			else
+				wRate = wFB_Opt1[FB_RATE0][wRate];
+
+			uNextPktTime = s_uGetTxRsvTime(pDevice, byPktType,
+						       len, wRate, bNeedAck);
 		}
 
 		return pDevice->uSIFS + uAckTime + uNextPktTime;