Simplify le_pack_PackString() implementation
Simplify le_pack_PackString() implementation

Removes call to memccpy and replaces with a loop.  This simplifies the logic
and removes an unnecessary function call.

Resolves: LE-7296
Change-Id: Ibb2272c19042baaa054b076e255720412b7c28de

legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af