mtd: rawnand: tegra: Simplify maximum determination in tegra_nand_setup_timing()

[Markus Elfring]

>> You would eventually like to express that a maximum should be determined
>> from three (or even four?) values.
>
> If there was a max4(), why not, but in this case I don't see the point.
Do you miss such a programming interface so far?
Would you be looking for corresponding software adjustments?

Regards,
Markus