Fix: verbose build for external components

LazyFetch allows setting <upper case component name>_VERBOSE_BUILD
variable in the cache or in the environment to make the build emit all
build commands executed. This is not working as the code uses an
incorrect variable.
Fix the variable and make the feature work.

Signed-off-by: Gyorgy Szing <gyorgy.szing@arm.com>
Change-Id: I14b88ef364ac08548edcc9aee4b8ce28a40f5a01
diff --git a/tools/cmake/common/LazyFetch.cmake b/tools/cmake/common/LazyFetch.cmake
index 0c00bce..577bd45 100644
--- a/tools/cmake/common/LazyFetch.cmake
+++ b/tools/cmake/common/LazyFetch.cmake
@@ -140,7 +140,7 @@
 	endif()
 
 	if (DEFINED ${UC_DEP_NAME}_VERBOSE_BUILD OR DEFINED ENV{${UC_DEP_NAME}_VERBOSE_BUILD})
-		set(_CMAKE_VERBOSE_CFG_FLAG "--verbose")
+		set(_CMAKE_VERBOSE_BLD_FLAG "--verbose")
 	endif()
 
 	if (BUILD_INSTALL_DIR)