Update marbl_ciso_interior_tendency_mod.F90

[jlinmod]

Fixed comments, eps_aq_g equation error (Zhang et al., 1995), and cell surface area unit conversion fix for calcifier (Popp et al., 1998).

[mnlevy1981]

As in #465 (comment), line 355 was correct before you added the negative sign but if you revert that change then we'd be happy to update all of your comments.

Also note that your change to cell_surf(auto_ind) in line 836 is inside an entire block of commented-out code; as the comment mentions, we don't know these values for explicit calcifiers yet, so those autotrophs continue to use the defaults for small phytoplankton (where cell_surf(auto_ind) = 87.6e-12_r8). I would suggest reverting line 836 as well, and we'll make sure cell_surf(auto_ind) is set correctly when we are ready to use different values for all the cell_ variables for explicit calcifiers.