net: dsa: realtek: remove unnecessary file, dentry, inode declarations

These are present since commit d8652956 ("net: dsa: realtek-smi: Add
Realtek SMI driver") and never needed. Apparently the driver was not
cleaned up sufficiently for submission.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patch.msgid.link/20250813181023.808528-1-vladimir.oltean@nxp.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>