boot/Kconfig: fix comments syntax error

Fix comments syntax error in SPL_LOAD_FIT_APPLY_OVERLAY description.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Kconfig b/boot/Kconfig
index d95a2a7..8c27f52 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -231,7 +231,7 @@
 	depends on SPL_LOAD_FIT
 	select OF_LIBFDT_OVERLAY
 	help
-	  The device tree is loaded from the FIT image. Allow the SPL is to
+	  The device tree is loaded from the FIT image. Allow the SPL to
 	  also load device-tree overlays from the FIT image an apply them
 	  over the device tree.