nimble/ll: Improve handling of incomplete adv data
nimble/ll: Improve handling of incomplete adv data

As per Core specification [1], if advertising data is not complete in
advertising set we should return Command Disallowed error when trying to
enable set.

[1] 5.0, Vol 2, Part E, section 7.8.56

mlaz/mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,mlaz/mynewt-core,andrzej-kaczmarek/apache-mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,andrzej-kaczmarek/apache-mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,mlaz/mynewt-core,andrzej-kaczmarek/apache-mynewt-core,andrzej-kaczmarek/apache-mynewt-core,andrzej-kaczmarek/incubator-mynewt-core,andrzej-kaczmarek/incubator-mynewt-core