m68k: handle presence of 64bit mul/div instructions cleanly

The traditional 68000 processors and the newer reduced instruction set
ColdFire processors do not support the 32*32->64 multiply or the 64/32->32
divide instructions. This is not a difference based on the presence of
a hardware MMU or not.

Create a new config symbol to mark that a CPU type doesn't support the
longer multiply/divide instructions. Use this then as a basis for using
the fast 64bit based divide (in div64.h) and for linking in the extra
libgcc functions that may be required (mulsi3, divsi3, etc).

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/include/asm/div64.h

@@ -1,7 +1,9 @@
 #ifndef _M68K_DIV64_H
 #define _M68K_DIV64_H
 
-#ifdef CONFIG_MMU
+#ifdef CONFIG_CPU_HAS_NO_MULDIV64
+#include <asm-generic/div64.h>
+#else
 
 #include <linux/types.h>
 
@@ -27,8 +29,6 @@
 	__rem;							\
 })
 
-#else
-#include <asm-generic/div64.h>
-#endif /* CONFIG_MMU */
+#endif /* CONFIG_CPU_HAS_NO_MULDIV64 */
 
 #endif /* _M68K_DIV64_H */