ANDROID: sdcardfs: remove unnecessary call to do_munmap

Adapted from wrapfs
commit 5be6de9ecf02 ("Wrapfs: use vm_munmap in ->mmap")
commit 2c9f6014a8bb ("Wrapfs: remove unnecessary call
to vm_unmap in ->mmap")

Code is unnecessary and causes deadlocks in newer kernels.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Bug: 35766959
Change-Id: Ia252d60c60799d7e28fc5f1f0f5b5ec2430a2379

fs/sdcardfs/file.c

@@ -176,12 +176,6 @@ static int sdcardfs_mmap(struct file *file, struct vm_area_struct *vma)
 			goto out;
 		}
 		saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */
-		err = do_munmap(current->mm, vma->vm_start,
-				vma->vm_end - vma->vm_start);
-		if (err) {
-			pr_err("sdcardfs: do_munmap failed %d\n", err);
-			goto out;
-		}
 	}
 
 	/*