ahc: eliminate AHC*_CALL macros

ahc: eliminate AHC*_CALL macros

Currently, we use AHC*_CALL macros to call many of the Camera functions.
However, we already have helper classes to call the Camera functions, so
eliminate the macros.

As a nice side-benefit, we also get improved error handling and
reporting when something goes wrong calling these functions, because a
GError gets populated, and we log a GST_ERROR when something fails. This
was harder to do using macros, as all error handling was hidden from the
caller.

https://bugzilla.gnome.org/show_bug.cgi?id=763065