product/morello: supress Cppcheck error on macro substitution

Added a new Cppcheck suppression entry for a syntax error in Morello,
specifically for the macro expansion of `BUILD_VERSION_DESCRIBE_STRING`.

Signed-off-by: Leandro Belli <leandro.belli@arm.com>
Change-Id: I6d996fcc24942fd7cc42ce3746400d50bdcc4b31