powerpc64: convert to dynamic percpu allocator

Now that percpu allows arbitrary embedding of the first chunk,
powerpc64 can easily be converted to dynamic percpu allocator.
Convert it.  powerpc supports several large page sizes.  Cap atom_size
at 1M.  There isn't much to gain by going above that anyway.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 61bbffa..2c42e15 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -46,10 +46,10 @@
 	bool
 	default y
 
-config HAVE_LEGACY_PER_CPU_AREA
+config HAVE_SETUP_PER_CPU_AREA
 	def_bool PPC64
 
-config HAVE_SETUP_PER_CPU_AREA
+config NEED_PER_CPU_EMBED_FIRST_CHUNK
 	def_bool PPC64
 
 config IRQ_PER_CPU