include: reset: Change to use CONFIG_IS_ENABLED(DM_RESET)

Change to use CONFIG_IS_ENABLED(DM_RESET), so this can work in SPL
build (CONFIG_SPL_DM_RESET) and U-boot build (CONFIG_DM_RESET).

Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/reset.h

@@ -77,7 +77,7 @@ struct reset_ctl_bulk {
 	unsigned int count;
 };
 
-#ifdef CONFIG_DM_RESET
+#if CONFIG_IS_ENABLED(DM_RESET)
 /**
  * reset_get_by_index - Get/request a reset signal by integer index.
  *