hw/net/cadence_gem: use REG32 macro for register definitions Replace register defines with the REG32 macro from registerfields.h in the Cadence GEM device. Signed-off-by: Luc Michel <luc.michel@amd.com> Reviewed-by: sai.pavan.boddu@amd.com Message-id: 20231017194422.4124691-2-luc.michel@amd.com Signed-off-by: Peter Maydell <peter.maydell@linaro.org>