percpu: rename 4k first chunk allocator to page

Page size isn't always 4k depending on arch and configuration.  Rename
4k first chunk allocator to page.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David Howells <dhowells@redhat.com>
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index e134c82..7989f61 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -74,7 +74,7 @@
 				size_t static_size, size_t reserved_size,
 				ssize_t dyn_size);
 
-extern ssize_t __init pcpu_4k_first_chunk(
+extern ssize_t __init pcpu_page_first_chunk(
 				size_t static_size, size_t reserved_size,
 				pcpu_fc_alloc_fn_t alloc_fn,
 				pcpu_fc_free_fn_t free_fn,