fwk: fix missing references for `FWK_LOG_LEVEL_TRACE`

This patch addresses an issue where a reference was missing after
renaming from `FWK_LOG_LEVEL_DEBUG` to `FWK_LOG_LEVEL_TRACE`.
The fix ensures all references are properly updated.

Signed-off-by: Leandro Belli <leandro.belli@arm.com>
Change-Id: Icf1ea1386bb9cbaf4f04b875d3194c5b18cda2bd