Fix splitscreen Title Card act name regression

This merge request fixes a regression caused by commit 5568e445 ("Colored title cards").

That commit set stplyr to &players[consoleplayer] at the start of ST_drawTitleCard() in order to get the local player's colour... but stplyr is checked later in the same function, both for the sake of checking whether player 1 or player 2's title card is being drawn, and for offsetting the act name downwards with V_PERPLAYER so that the act name is shown on both players' views. Neither of those things happen in v2.2.3, due to stplyr being set to player 1 first.

This merge request fixes that, by not setting stplyr to anything, and instead checking players[consoleplayer] directly.
(Note that colormap currently doesn't apply to anything drawn for player 2, so it's okay that colormap only matches player 1.)