mm: fix docs for the kernel parameter ``thp_anon=``

mainline inclusion
from mainline-v6.12-rc1
commit 652e1a51465f2e8e75590bc3dd1e3a3b61020568
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/IB66DA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=652e1a51465f2e8e75590bc3dd1e3a3b61020568

--------------------------------

If we add ``thp_anon=32,64K:always`` to the kernel command line, we
will see the following error:

[    0.000000] huge_memory: thp_anon=32,64K:always: error parsing string, ignoring setting

This happens because the correct format isn't ``thp_anon=<size>,<size>[KMG]:<state>```,
as [KMG] must follow each number to especify its unit. So, the correct
format is ``thp_anon=<size>[KMG],<size>[KMG]:<state>```.

Therefore, adjust the documentation to reflect the correct format of the
parameter ``thp_anon=``.

Link: https://lkml.kernel.org/r/20241101165719.1074234-3-mcanal@igalia.com


Fixes: dd4d30d1cdbe ("mm: override mTHP "enabled" defaults at kernel cmdline")
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Acked-by: Barry Song <baohua@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Wang Lian <dev01404@linx-info.com>
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