m68k: make support for FPU hardware configurable

The classic m68k code has always supported an FPU (although it may have
been a software emulated one). The non-MMU m68k code has never supported FPU
hardware. To help in merging common code create a configation setting that
signifies if we are builing in FPU support or not.

This switch, CONFIG_FPU, is set as per the current use cases. So it is
always enabled if CONFIG_MMU is set, and disabled otherwise. With a little
extra code it will be possible to disable it on the classic m68k platforms
as well, and to enable it on non-MMU platforms that do have hardware FPU.

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

arch/m68k/Kconfig

@@ -7,6 +7,7 @@ config M68K
 	select GENERIC_IRQ_SHOW
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if RMW_INSNS
 	select GENERIC_CPU_DEVICES
+	select FPU if MMU
 
 config RWSEM_GENERIC_SPINLOCK
 	bool
@@ -64,6 +65,9 @@ config CPU_HAS_NO_MULDIV64
 config CPU_HAS_ADDRESS_SPACES
 	bool
 
+config FPU
+	bool
+
 config HZ
 	int
 	default 1000 if CLEOPATRA