dtc: Make dtc_open_file() die() if unable to open requested file

All current callers of dtc_open_file() immediately die() if it returns
an error.  In a non-interative tool like dtc, it's hard to see what
you could sensibly do to recover from a failure to open an input file
in any case.

Therefore, make dtc_open_file() itself die() if there's an error
opening the requested file.  This removes the need for error checking
at the callsites, and ensures a consistent error message in all cases.
While we're at it, change the rror message from fstree.c when we fail
to open the input directory to match dtc_open_file()'s error message.

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