Staging: pi433: Merge assignment with return value

Removes the unnecessary assignment of retval preceding
the return statement.

Detected using the following Coccinelle script:
@@
local idexpression ret;
expression e;
@@

-ret =
+return
     e;
-return ret;
Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/pi433/rf69.c

@@ -690,9 +690,7 @@ int rf69_set_preamble_length(struct spi_device *spi, u16 preambleLength)
 	/* transmit to chip */
 	retval = WRITE_REG(REG_PREAMBLE_MSB, msb);
 	if (retval) return retval;
-	retval = WRITE_REG(REG_PREAMBLE_LSB, lsb);
-
-	return retval;
+	return WRITE_REG(REG_PREAMBLE_LSB, lsb);
 }
 
 int rf69_set_sync_enable(struct spi_device *spi, enum optionOnOff optionOnOff)