m68k/mac: Export Peripheral System Controller (PSC) base address to modules

If CONFIG_MACMACE=m:

    ERROR: psc [drivers/net/ethernet/apple/macmace.ko] undefined!

Add the missing export to fix this.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/m68k/mac/psc.c b/arch/m68k/mac/psc.c
index cd38f29..2290c0c 100644
--- a/arch/m68k/mac/psc.c
+++ b/arch/m68k/mac/psc.c
@@ -29,6 +29,7 @@
 
 int psc_present;
 volatile __u8 *psc;
+EXPORT_SYMBOL_GPL(psc);
 
 /*
  * Debugging dump, used in various places to see what's going on.