unicore32: change PERCPU to PERCPU_SECTION

The patch changes PERCPU to PERCPU_SECTION
see commit from Tejun Heo <0415b00d175e0d8945e6785aad21b5f157976ce0>
  percpu: Always align percpu output section to PAGE_SIZE

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: Tejun Heo <tj@kernel.org>

arch/unicore32/kernel/vmlinux.lds.S

@@ -30,7 +30,7 @@ SECTIONS
 	HEAD_TEXT_SECTION
 	INIT_TEXT_SECTION(PAGE_SIZE)
 	INIT_DATA_SECTION(16)
-	PERCPU(L1_CACHE_BYTES, PAGE_SIZE)
+	PERCPU_SECTION(L1_CACHE_BYTES)
 	__init_end = .;
 
 	_stext = .;