cam: scsi_enc_ses: Remove an unnecessary VLA construction

[cem]

Summary

The array size is known at compile time; we don't need a C variable-length
array. Extract the constant into a short-lived macro and use it to size the
array. Pull the array out to function scope while here.

[jhb]

*shrug* Given the function already defines variables in scope I'm not sure it really matters to pull it out to the top-level (esp in light of the recent style(9) change Warner is working on). Presumably this is all the same for the compiler anyway?

[cem]

In D24856#560905, @jhb wrote:

*shrug* Given the function already defines variables in scope I'm not sure it really matters to pull it out to the top-level (esp in light of the recent style(9) change Warner is working on).

It doesn’t have to be top-level in light of the more recent style9 developments.

Presumably this is all the same for the compiler anyway?

Initially I wrote this because sparse is a dumber compiler and didn’t have a good way to disable a Werror vla warning, but I’ve extended that tool to make it optional. So this change isn’t a big deal either way; the VLA construction is unnecessary either way.