staging: r8188eu: rtw_action_public_decache's token is a u8

Both callers of rtw_action_public_decache pass a u8 value for the token
parameter. We can change token from s32 to u8 and remove the code for
token < 0.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20221030173326.1588647-13-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>