fix memory leak.  what is the advantage of dynamic allocation here?

Reference: /n/sources/patch/applied/bitsy-pcmcia-leak
Date: Sat Jun 30 01:33:18 CES 2007
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/bitsy/devpcmcia.c	Sat Jun 30 01:32:12 2007
+++ /sys/src/9/bitsy/devpcmcia.c	Sat Jun 30 01:32:07 2007
@@ -407,6 +407,7 @@
 		if(devtab[dtx]->config(1, p, &cf) < 0)
 			error("couldn't configure device");
 		sp->dev = devtab[dtx];
+		free(cf.type);
 		wunlock(sp);
 		poperror();