mesh: beacon: Remove unnecessary #ifdefs
mesh: beacon: Remove unnecessary #ifdefs

Static variables and functions don't need #ifdefs if the code calling
them is using IS_ENABLED(). If IS_ENABLED() evaluates to false the
compiler will strip out all the static entities.

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble