selftests/bpf/test_lirc_mode2.sh: Exit with proper code

stable inclusion
from stable-v5.10.110
commit 75a4a97b7463029d95acb422d630a53ee3ff28f3
bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=75a4a97b7463029d95acb422d630a53ee3ff28f3



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[ Upstream commit ec80906b ]

When test_lirc_mode2_user exec failed, the test report failed but still
exit with 0. Fix it by exiting with an error code.

Another issue is for the LIRCDEV checking. With bash -n, we need to quote
the variable, or it will always be true. So if test_lirc_mode2_user was
not run, just exit with skip code.

Fixes: 6bdd533c ("bpf: add selftest for lirc_mode2 type program")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220321024149.157861-1-liuhangbin@gmail.com


Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>