Fix: ext4_discard_preallocations changed in linux 6.8.0-rc3

See upstream commit:

    commit f0e54b6087de9571ec61c189d6c378b81edbe3b2
    Author: Kemeng Shi <shikemeng@huaweicloud.com>
    Date:   Fri Jan 5 17:21:02 2024 +0800

        ext4: remove 'needed' in trace_ext4_discard_preallocations

        As 'needed' to trace_ext4_discard_preallocations is always 0 which
        is meaningless. Just remove it.

Change-Id: Ib6b698ca553c4beebd4ca791c83bbbb927901758
Signed-off-by: Kienan Stewart <kstewart@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>