rtase: Correct the speed for RTL907XD-V1

[ Upstream commit c1fc14c4df801fe2d9ec3160b52fa63569ce164c ]

Previously, the reported speed was uniformly set to SPEED_5000, but the
RTL907XD-V1 actually operates at a speed of SPEED_10000. Therefore, this
patch makes the necessary correction.

Fixes: dd7f17c4 ("rtase: Implement ethtool function")
Signed-off-by: Justin Lai <justinlai0215@realtek.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>