i2c: designware: Replace magic numbers with named constants

i2c: designware: Replace magic numbers with named constants

Replace various magic numbers with properly named constants to improve
code readability and maintainability. This includes constants for
register access, timing adjustments, timeouts, FIFO parameters,
and default values.

This makes the code more self-documenting without altering any
functionality.

Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20251211122947.1469666-1-a.shimko.dev@gmail.com