dfly-2.2.0-REL: Installer Bug

[M.K.]

OS: dfly-2.2.0-REL

Installer quits when you try to install using part of disk (i.e. using 
partition no. 2, 3 or 4 for dfly).

Reason: missing device nodes for disk label letters.

Fix: manually add disk label device nodes before running installer.

e.g.:
# ./MAKEDEV ad0s2a
# ./MAKEDEV ad0s3a
# ./MAKEDEV ad0s4a
Note: Doing it just for "a" makes all the other letters as well.