Revert "ANDROID: export symbols for zram module"

This reverts commit a3654ae7c1.

It has merge conflicts with upstream patches in v7.0. It can be later
reapplied if needed.

Bug: 421065577
Cc: Richard Chang <richardycc@google.com>
Change-Id: I69cbdf92162a2c2c273331e00531aacd725d0b72
Signed-off-by: Carlos Llamas <cmllamas@google.com>

kernel/fork.c

@@ -1421,7 +1421,6 @@ struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
 
 	return mm;
 }
-EXPORT_SYMBOL_GPL(mm_access);
 
 static void complete_vfork_done(struct task_struct *tsk)
 {

kernel/pid.c

@@ -640,7 +640,6 @@ struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags)
 	*flags = f_flags;
 	return task;
 }
-EXPORT_SYMBOL_GPL(pidfd_get_task);
 
 /**
  * pidfd_create() - Create a new pid file descriptor.

mm/pagewalk.c

@@ -584,7 +584,6 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 
 	return walk_page_range_mm_unsafe(mm, start, end, ops, private);
 }
-EXPORT_SYMBOL_GPL(walk_page_range);
 
 /**
  * walk_kernel_page_table_range - walk a range of kernel pagetables.

mm/pgtable-generic.c

@@ -407,7 +407,6 @@ again:
 	pte_unmap_unlock(pte, ptl);
 	goto again;
 }
-EXPORT_SYMBOL_GPL(pte_offset_map_lock);
 
 #ifdef CONFIG_ASYNC_KERNEL_PGTABLE_FREE
 static void kernel_pgtable_work_func(struct work_struct *work);

mm/swapfile.c

@@ -1613,7 +1613,6 @@ put_out:
 	percpu_ref_put(&si->users);
 	return NULL;
 }
-EXPORT_SYMBOL_GPL(get_swap_device);
 
 static void swap_entries_put_cache(struct swap_info_struct *si,
 				   swp_entry_t entry, int nr)