staging: r8188eu: convert rtw_p2p_get_role to return void

rtw_p2p_get_role always returns 0 and it's return value is not used.
Convert it to return void.

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
Link: https://lore.kernel.org/r/dcd4bba9910b172031ccc0f138c78e8471e36d91.1643466748.git.abdun.nihaal@gmail.com


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