Clean up reference tank information table

Clean up reference tank information table

This makes the reference tanks ("struct tank_info") use a saner format
which specifies explicitly whether the size is in ml or cubic feet, and
whether the pressure is in psi or bar.

So instead of having magic rules ("size is in cuft if < 1000, otherwise
mliter"), just set the size explicitly:

	{ "11.1 l", .ml = 11100 },
	{ "AL80",  .cuft =  80, .psi = 3000 },

and then the code can just convert to standard measurements without any
odd rules, and the initialization table becomes self-explanatory too.

This is in preparation for doing the metric tanks with pressure: Henrik
Aronsen sent a really ugly patch using the previous setup, I just
couldn't stand the additional hackery.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>