greybus: Remove unused VERSION specific macros

We don't use these anymore. Drop them.

Note that some macro's specific to bridged PHY devices aren't removed in
the patch, as gbsim will break otherwise. They will be removed
separately.

Compile tested.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>