Documentation: zram: fix the description about orig_data_size of mm_stat

orig_data_size counted the same_pages by commit 51f9f82c ("zram:
count same page write as page_stored"), so let's fix it.
Signed-off-by: Yue Hu <zbestahu@163.com>
Link: https://lore.kernel.org/r/20200206111031.9524-1-zbestahu@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/blockdev/zram.rst

@@ -251,8 +251,6 @@ line of text and contains the following stats separated by whitespace:
 
  ================ =============================================================
  orig_data_size   uncompressed size of data stored in this disk.
-		  This excludes same-element-filled pages (same_pages) since
-		  no memory is allocated for them.
                   Unit: bytes
  compr_data_size  compressed size of data stored in this disk
  mem_used_total   the amount of memory allocated for this disk. This