m68k: Kill several external declarations in source files

  - Replace external declarations by proper includes where availiable.
    The accesses to some symbols had to be modified, as before they were
    declared using e.g. "extern int _end", while asm-generic/sections.h uses
    e.g. "extern char _end[]"
  - Remove unused or superfluous external declarations

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index f01d418..dfffb9c 100644
--- a/arch/m68k/mac/via.c
+++ b/arch/m68k/mac/via.c
@@ -34,6 +34,7 @@
 #include <asm/macints.h>
 #include <asm/mac_via.h>
 #include <asm/mac_psc.h>
+#include <asm/mac_oss.h>
 
 volatile __u8 *via1, *via2;
 int rbv_present;
@@ -84,7 +85,6 @@
 void via_irq_clear(int irq);
 
 extern irqreturn_t mac_scc_dispatch(int, void *);
-extern int oss_present;
 
 /*
  * Initialize the VIAs