ddr: altera: Internal mem_calibrate() cleanup part 1

This is kind of microseries-within-series indent cleanup.
Rework the code for the first loop within the middle-loop
of the mega-loop to make it actually readable and not an
insane cryptic pile of indent failure.

It is likely that this patch has checkpatch warnings, but
for the sake of not breaking the code, these are ignored.

No functional change.

Signed-off-by: Marek Vasut <marex@denx.de>