platsupport: Remove cmake warning for missing file

As it isn't an error for queried files to not exist, a
warning message is a bit misleading.

Signed-off-by: Kent McLeod <kent@kry10.com>

libplatsupport/tools/helpers.cmake

diff --git a/libplatsupport/tools/helpers.cmake b/libplatsupport/tools/helpers.cmake
index 7515957..991abad 100644
--- a/libplatsupport/tools/helpers.cmake
+++ b/libplatsupport/tools/helpers.cmake
@@ -19,9 +19,6 @@
         PATHS "${platsupport_tools}/device_lists/${device_type}"
         CMAKE_FIND_ROOT_PATH_BOTH
     )
-    if("${${platform}_${device_type}_LIST}" STREQUAL "${platform}_${device_type}_LIST-NOTFOUND")
-        message(WARNING "Could not find device list for device type ${device_type} for ${platform}")
-    endif()
     set(${var} ${${platform}_${device_type}_LIST} PARENT_SCOPE)
 endfunction()