Add AVC HTTP timeout to Kconfig
Add AVC HTTP timeout to Kconfig

In a slow cellular network, AVC HTTP timeout is critical to the download
performance in the ThreadX platform. In stead of using a constant across
platforms, we add the timeout setting to Kconfig so that we can
fine-tune the value for each platform.

Resolves: LE-14650
Change-Id: Ib892c9507a1b69871841b646ec3028f4f6b5fbbd

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