powerpc: move math-emu over to arch/powerpc

Towards the goal of having arch/powerpc not build anything over in arch/ppc
move math-emu over.  Also, killed some references to arch/ppc/ in the
arch/powerpc Makefile which should belong in drivers/ when the particular
sub-arch's move over to arch/powerpc.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/Makefile

@@ -129,12 +129,8 @@ core-y				+= arch/powerpc/kernel/ \
 				   arch/powerpc/lib/ \
 				   arch/powerpc/sysdev/ \
 				   arch/powerpc/platforms/
-core-$(CONFIG_MATH_EMULATION)	+= arch/ppc/math-emu/
+core-$(CONFIG_MATH_EMULATION)	+= arch/powerpc/math-emu/
 core-$(CONFIG_XMON)		+= arch/powerpc/xmon/
-core-$(CONFIG_APUS)		+= arch/ppc/amiga/
-drivers-$(CONFIG_8xx)		+= arch/ppc/8xx_io/
-drivers-$(CONFIG_4xx)		+= arch/ppc/4xx_io/
-drivers-$(CONFIG_CPM2)		+= arch/ppc/8260_io/
 
 drivers-$(CONFIG_OPROFILE)	+= arch/powerpc/oprofile/