Always print file and line number in panic/unreachable macros

Release builds used to have a special variant of these macros without
the source code location information. This kind of mechanism is useful
when writing software that needs both a development and production
version so that the source code information is not leaked when the
device is in the field.

However, in the context of TF-A Tests, it makes little sense, as it's
unlikely somebody would ever ship a device with TF-A Tests installed
on it.

Change-Id: Ic14ad87c2756762807ee71142f21d6973233144e
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>