tools: remove redundant ethtool.h from tooling infra

Remove the redundant ethtool.h header file from tools/include/uapi/linux.
The file is unnecessary as the system uses the kernel's
include/uapi/linux/ethtool.h directly.

Signed-off-by: Tushar Vyavahare <[email protected]>
Acked-by: Jakub Kicinski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: tvyavaha