Add tankpressure parsing for UDDF files

David McNett sent me some example Cochran CAN file data, along with his
UDDF exports of same.  I still have absolutely no idea how to decode the
CAN files (although the subsurface decrypting code seems to correctly
decrypt the data, and I see binary patters rather than just noise), but
at least I can make sure we parse the UDDF portion better.

See also

  https://github.com/nugget/cochran2uddf

for David's tool to convert the Cochran CSV exports into UDDF.

Data-source: David McNett <nugget@macnugget.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>