Interpolated pressure should always be set

Interpolated pressure should always be set, even it we didn't
calculate a new one. In this case we should just use the last one.

Signed-off-by:Rodrigo Severo <rodrigo@fabricadeideias.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add unit-aware conversion of pressure data

This just adds (and uses) a string_to_pressure() to parse pressure units
correctly when filling in cylinder pressures.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>