jhead: Add handling for short tags with unknown length

Part of the fix for b/5582076

SHORT tags with a variable length need to be places in
the data write section.

Fixes issue with ISOSpeedRating not being inserted
correctly.

Change-Id: I9b1810de9102f2e2d63eca1a90547aba7e18a0d7
Signed-off-by: Tyler Luu <tluu@ti.com>
Signed-off-by: Iliyan Malchev <malchev@google.com>
1 file changed