Revert "dm: always update the array size in realloc_argv on success"

This reverts commit 64e95bb3 which is
commit 5a2a6c42 upstream.

It breaks the Android kernel testing and can be brought back in the
future in an safe way if it is really needed.

Bug: 161946584
Change-Id: Ie1931ea6687fa16b4575e4d44c5910a871f9b0de
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>