staging: r8188eu: make _rtw_init_mlme_priv static

The _rtw_init_mlme_priv function is used only in rtw_mlme.c.
It can be declared as static.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220322202439.157999-2-martin@kaiser.cx


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