This documentation is well-intentioned but not good advice.
The reason why we have a vtable-like API abstraction at the
driver subsystem level is to introduce object orientation.
The subsystem defintions implement an abstract class that
specific driver implementations all implement, providing
a common interface for end users. Multiple drivers may be
written for a subsystem that are interchangeable to the end
user.
However, there is no point in introducing a vtable-like
abstraction for APIs which are specific to a single driver.
We are not trying to present an interface abstraction which
could support multiple implementations. There is just one.
Simply declare a function in a header, and implement it in
the driver's C file.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>