Assorted cleanups and extensions for ftdump

[Jon Loeliger]

> This patch makes a number of minor changes to the ftdump debugging
> tool.
> 
>  * There was an endian bug in one place, which this fixes.
> 
>  * We now use const qualifiers in a number of places where we can
> 
>  * ftdump can now be instructed to read from stdin by giving "-" as
>    the filename.
> 
>  * The buffer into which the blob is read is increased from 16k to
>    64k, and is now dynamically allocated.
> 
>  * ftdump now emits source in dts-v1 format
> 
> Since ftdump is little used these days, these fixes are arguably of
> little use.  On the other hand, I already did the work of making the
> changes some time back, so I guess we might as well fold these small
> fixes and improvements in.
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Applied.

jdl