usbdebug: Use fixed size field

The structure is placed inside CBMEM, one should
use types with fixed size. Seems we prefer to
prepare for 64-bit builds even for MMIO pointers.

Change-Id: I60382664a53650b225abc1f77c87ed4e121d429e
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/31182
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/arch/x86/car.ld

@@ -68,7 +68,7 @@
 #endif
 	_car_ehci_dbg_info_start = .;
 	/* Reserve sizeof(struct ehci_dbg_info). */
-        . += 88;
+        . += 80;
         _car_ehci_dbg_info_end = .;
 	/* _car_global_start and _car_global_end provide symbols to per-stage
 	 * variables that are not shared like the timestamp and the pre-ram