[1.1.x] EEprom code cleanup

[GMagician]

#10710 counterpart

[GMagician]

@thinkyhead just a question, what's the benefit of 'const' vs 'not const'?
does it shrink code?

[thinkyhead]

@GMagician — Adding const to function and method arguments can help with binding optimizations, especially for extern linkage that wouldn't otherwise know. Adding const to variables that won't change within a method or function can help compilers with load, spill, and loop invariance optimizations.

In terms of compilation, very often the compiler can tell after the first pass that a variable isn't being altered by the subsequent code, and it can optimize on the second pass just as it would if there was a const specifier, but I like to add const so human readers can see from the start that a value won't change, and so the compiler doesn't need to finish the first pass to know it won't change. And of course, it makes the compiler bark if you do try to alter it, which can sometimes be useful.