realtek: pcs: rtl930x: drop superfluous debug prints

realtek: pcs: rtl930x: drop superfluous debug prints

The RTL930x calibration code is especially chatty. There are debug
prints for every start and end of a section corresponding to the
sections the SDK uses. In the end, this doesn't help a user much and
just wastes CPU cycles. Moreover it doesn't help in understand what is
done there. As a first step, drop "start" and "end" prints but preserve
their meaning as comments.

While at it, slightly adjust two other prints and drop one confusing
print.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23288
Signed-off-by: Robert Marko <robimarko@gmail.com>