Merge branch 'dsa-mxl-gsw1xx-support-r-g-mii-slew-rate-configuration'

Alexander Sverdlin says:

====================
dsa: mxl-gsw1xx: Support R(G)MII slew rate configuration

Maxlinear GSW1xx switches offer slew rate configuration bits for R(G)MII
interface. The default state of the configuration bits is "normal", while
"slow" can be used to reduce the radiated emissions. Add the support for
the latter option into the driver as well as the new DT bindings.
====================

Link: https://patch.msgid.link/20260114104509.618984-1-alexander.sverdlin@siemens.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>