-Wpadded warns whenever the C compiler automatically includes any
padding in a structure. Because TF-A has a large number of structures,
this occurs fairly frequently and is incredibly verbose, and as such is
unlikely to ever be fixed.

The utility of this warning is also extremely limited - knowing that a
structure includes padding does not point to the existence of an error,
and is probably quite unlikely to indicate actually buggy behaviour.
Therefore, it's probably best to keep this warning off at all times.

Change-Id: I0797cb75f06b4fea0d2fdc16fd5ad978a31d76ec
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>