dtc: Make dt_from_blob() open its own input file, like the other input formats

Currently, main() has a variable for the input file.  It used to be
that main() would open the input based on command line arguments
before passing it to the dt_from_*() function.  However, only
dt_from_blob() uses this.  dt_from_source() opens its own file, and
dt_from_fs() interprets the argument as as a directory and does its
own opendir() call.

Furthermore, main() opened the file with dtc_open_file() but closed it
with a direct call to fclose().

Therefore, to improve the interface consistency between the
dt_from_*() functions, make dt_from_blob() open and close its own
files like the other dt_from_*() functions.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
3 files changed