To keep Interface API small, compact and readable, but versatile
and extensible at the same time 'Interface Features' are introduced.
Interface Features is a dynamic list of user definable driver extensions
that can provide additional functionalities to the interface driver.
Intelligent drivers can expose their hardware specific operations this way,
while generic drivers can get additional applications with use of external
libraries that will generate additional features (ie. LibSWD for SWD support).
Change-Id: Ibfa72b4906d854572dfeb365d28bc41e0b6c3538
Signed-off-by: Tomek CEDRO <cederom@tlen.pl>