bpf: Reorder bpf_prog_test_run_skb initialization

bpf: Reorder bpf_prog_test_run_skb initialization

This patch reorders the initialization of bpf_prog_test_run_skb to
simplify the subsequent patch. Program types are checked first, followed
by the ctx init, and finally the data init. With the subsequent patch,
program types and the ctx init provide information that is used in the
data init. Thus, we need the data init to happen last.

Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/063475176f15828a882c07846017394baf72f682.1760037899.git.paul.chaignon@gmail.com