Merge branch 'Simplify bpf_snprintf verifier code'

Florent Revest says:

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Alexei requested a couple of cleanups to the bpf_snprintf and
ARG_PTR_TO_CONST_STR verifier code.

https://lore.kernel.org/bpf/CABRcYmL_SMT80UTyV98bRsOzW0wBd1sZcYUpTrcOAV+9m+YoWQ@mail.gmail.com/T/#t


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Signed-off-by: Alexei Starovoitov <ast@kernel.org>