Use designated initializers for i2c_master_bus_config_t

## Problem

The  struct in  uses positional initializers which relies on struct field order rather than designated initializers. This makes the code fragile and not self-documenting.

## Suggested Fix

Use C++20 designated initializers:

# 0 "<stdin>"
# 0 "<built-in>"
# 0 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 0 "<command-line>" 2
# 1 "<stdin>"

## File

- 