tests/qtest/e1000e-test: Use e1000_regs.h

The register definitions in tests/qtest/e1000e-test.c had names
different from hw/net/e1000_regs.h, which made it hard to understand
what test codes corresponds to the implementation. Use
hw/net/e1000_regs.h from tests/qtest/libqos/e1000e.c to remove
these duplications.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20221103095416.110162-1-akihiko.odaki@daynix.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>