UPSTREAM: mb/lenovo/s230u: Fix USBDEBUG check

- Change preprocessor #if to standard C if.  This will get optimized
out if the config option is disabled, but lets the compiler check the
contents.
- CONFIG_USBDEBUG is always going to be defined even if it's disabled,
so this check is not going to work as expected.
See the coreboot Kconfig documentation in /Documentation/core/Kconfig.md

BUG=none
BRANCH=none
TEST=none

Change-Id: I57ae98d60f240b92d1e2fd9146c95c2928631db5
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 5ef5c00704
Original-Change-Id: Ia63438d9525e79307d9229ad3ffa2962978611d8
Original-Signed-off-by: Martin Roth <martinroth@google.com>
Original-Reviewed-on: https://review.coreboot.org/18974
Original-Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Original-Reviewed-by: Philippe Mathieu-Daud <philippe.mathieu.daude@gmail.com>
Original-Tested-by: build bot (Jenkins)
Reviewed-on: https://chromium-review.googlesource.com/459506

src/mainboard/lenovo/s230u/romstage.c

@@ -51,10 +51,9 @@ void pch_enable_lpc(void)
 		CONFIG_EC_BASE_ADDRESS | 1);
 	pci_write_config16(PCI_DEV(0, 0x1f, 0), 0xd8, 0xffc0);
 
-	#ifdef CONFIG_USBDEBUG
 	/* Enable external USB port power. */
-	ec_mm_set_bit(0x3b, 4);
-	#endif
+	if (IS_ENABLED(CONFIG_USBDEBUG))
+		ec_mm_set_bit(0x3b, 4);
 }
 
 void rcba_config(void)