powerpc/vdso: Remove get_page() in vdso_pagelist initialization

Partly copied from commit 16fb1a9b ("arm64: vdso: clean up
vdso_pagelist initialization").

No need to get_page() the vdso text/data - these are part of the
kernel image.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/9d14540bd10832b6c9519d74fb5728fdc4974b36.1601197618.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/vdso.c

@@ -748,7 +748,7 @@ static int __init vdso_init(void)
 	BUG_ON(vdso32_pagelist == NULL);
 	for (i = 0; i < vdso32_pages; i++) {
 		struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
-		get_page(pg);
+
 		vdso32_pagelist[i] = pg;
 	}
 	vdso32_pagelist[i++] = virt_to_page(vdso_data);
@@ -761,15 +761,13 @@ static int __init vdso_init(void)
 	BUG_ON(vdso64_pagelist == NULL);
 	for (i = 0; i < vdso64_pages; i++) {
 		struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
-		get_page(pg);
+
 		vdso64_pagelist[i] = pg;
 	}
 	vdso64_pagelist[i++] = virt_to_page(vdso_data);
 	vdso64_pagelist[i] = NULL;
 #endif /* CONFIG_PPC64 */
 
-	get_page(virt_to_page(vdso_data));
-
 	smp_wmb();
 	vdso_ready = 1;