af-binder: Fix const issue in afb-auth.h

af-binder: Fix const issue in afb-auth.h

The fields type and loa were declared as const.
This worked well for C compilers that are allowing
to initialize constant fixed structures.

But when compiling with C++, it is no more easy
to create initialized structure explicitely.
In C++, the solution is to use C++14 constexpr functions.
But for using these function, const must be removed.

Bug-AGL: SPEC-741

Change-Id: If5aca00e79dc074dcd1f6bac81a57d85b8537cea
Signed-off-by: José Bollo <jose.bollo@iot.bzh>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/10197
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-boot-test: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Matt Ranostay <matt.ranostay@konsulko.com>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Reviewed-by: Changhyeok Bae <changhyeok.bae@gmail.com>