powerpc/procfs: Propagate error of remap_pfn_range()

If the operation fails and userspace is unaware it will access unmapped
memory, crashing the process.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241010-vdso-generic-base-v1-22-b64f0842d512@linutronix.de

Author: t-8ch

arch/powerpc/kernel/proc_powerpc.c

@@ -33,10 +33,9 @@ static int page_map_mmap( struct file *file, struct vm_area_struct *vma )
 	if ((vma->vm_end - vma->vm_start) > PAGE_SIZE)
 		return -EINVAL;
 
-	remap_pfn_range(vma, vma->vm_start,
-			__pa(pde_data(file_inode(file))) >> PAGE_SHIFT,
-			PAGE_SIZE, vma->vm_page_prot);
-	return 0;
+	return remap_pfn_range(vma, vma->vm_start,
+			       __pa(pde_data(file_inode(file))) >> PAGE_SHIFT,
+			       PAGE_SIZE, vma->vm_page_prot);
 }
 
 static const struct proc_ops page_map_proc_ops = {