ethernet: ucc_geth: remove unused read of temoder field

In theory, such a read-after-write might be required by the hardware,
but nothing in the data sheet suggests that to be the case. The name
test also suggests that it's some debug leftover.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>