refactor(arm): add debug logs to show the reason behind skipping firmware config loading

Added debug logs to show the reason behind skipping firmware
configuration loading, and also a few debug strings were corrected.
Additionally, a panic will be triggered if the configuration sanity
fails.

Change-Id: I6bbd67b72801e178a14cbe677a8831b25a907d0c
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>