scripts/gdb: change kernel config dumping method

stable inclusion
from stable-v5.10.122
commit 13639c970fdb18ebfd621df71861a9d8b8491d53
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13639c970fdb18ebfd621df71861a9d8b8491d53



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[ Upstream commit 1f7a6cf6 ]

MAGIC_START("IKCFG_ST") and MAGIC_END("IKCFG_ED") are moved out
from the kernel_config_data variable.

Thus, we parse kernel_config_data directly instead of considering
offset of MAGIC_START and MAGIC_END.

Fixes: 13610aa9 ("kernel/configs: use .incbin directive to embed config_data.gz")
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>