staging: rtl8192u: simplify rtl819x_evm_dbtopercentage()

Use clamp() to simplify function rtl819x_evm_dbtopercentage() and
reduce object file size.
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20200118195305.16685-2-straube.linux@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/r8192U_core.c

@@ -3954,18 +3954,11 @@ static u8 rtl819x_query_rxpwrpercentage(s8 antpower)
 
 static u8 rtl819x_evm_dbtopercentage(s8 value)
 {
-	s8 ret_val;
+	s8 ret_val = clamp(-value, 0, 33) * 3;
 
-	ret_val = value;
-
-	if (ret_val >= 0)
-		ret_val = 0;
-	if (ret_val <= -33)
-		ret_val = -33;
-	ret_val = 0 - ret_val;
-	ret_val *= 3;
 	if (ret_val == 99)
 		ret_val = 100;
+
 	return ret_val;
 }