modpost: fix section mismatch check for exported init/exit sections

stable inclusion
from stable-v5.10.127
commit 959bbaf5b7a9cc5504b88e3a5b87a11937df6366
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5XDDK

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=959bbaf5b7a9cc5504b88e3a5b87a11937df6366



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commit 28438794 upstream.

Since commit f02e8a65 ("module: Sort exported symbols"),
EXPORT_SYMBOL* is placed in the individual section ___ksymtab(_gpl)+<sym>
(3 leading underscores instead of 2).

Since then, modpost cannot detect the bad combination of EXPORT_SYMBOL
and __init/__exit.

Fix the .fromsec field.

Fixes: f02e8a65 ("module: Sort exported symbols")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>