kallsyms: Reduce the memory occupied by kallsyms_seqs_of_names[]

[ Upstream commit 19bd8981 ]

kallsyms_seqs_of_names[] records the symbol index sorted by address, the
maximum value in kallsyms_seqs_of_names[] is the number of symbols. And
2^24 = 16777216, which means that three bytes are enough to store the
index. This can help us save (1 * kallsyms_num_syms) bytes of memory.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Stable-dep-of: b022f0c7 ("tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols")
Signed-off-by: Sasha Levin <sashal@kernel.org>