Merge branch 'net-dsa-microchip-fix-writes-to-phy-registers-0x10'

Rasmus Villemoes says:

====================
net: dsa: microchip: fix writes to phy registers >= 0x10

Patch 1 is just a simplification, technically unrelated to the other
two patches. But it would be a bit inconsistent to have the new
ksz_prmw32() introduced in patch 2 use ksz_rmw32() while leaving
ksz_prmw8() as-is.

The actual fix is of course patch 3. I can definitely see some weird
behaviour on our ksz9567 when writing to phy registers 0x1e and 0x1f
(with phytool from userspace), though it does not seem that the effect
is always to write zeroes to the buddy register as the errata sheet
says would be the case. In our case, the switch is connected via i2c;
I hope somebody with other switches and/or the SPI variants can test
this.
====================

Link: https://lore.kernel.org/r/20230620113855.733526-1-linux@rasmusvillemoes.dk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>