selftests: net: Explicitly enable CONFIG_CRYPTO_SHA1 for IPsec

xfrm_policy.sh, nft_flowtable.sh, and vrf-xfrm-tests.sh use 'ip xfrm'
with SHA-1, either 'auth sha1' or 'auth-trunc hmac(sha1)'. That
requires CONFIG_CRYPTO_SHA1, which CONFIG_INET_ESP intentionally doesn't
select (as per its help text). Previously, the config for these tests
relied on CONFIG_CRYPTO_SHA1 being selected by the unrelated option
CONFIG_IP_SCTP. Since CONFIG_IP_SCTP is being changed to no longer do
that, instead add CONFIG_CRYPTO_SHA1 to the configs explicitly.

Reported-by: Paolo Abeni <[e-mail]>
Closes: https://lore.kernel.org/r/[e-mail]
Suggested-by: Florian Westphal <[e-mail]>
Acked-by: Xin Long <[e-mail]>
Signed-off-by: Eric Biggers <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/config

···
 CONFIG_INET_DIAG=y
 CONFIG_INET_ESP=y
 CONFIG_INET_ESP_OFFLOAD=y
+CONFIG_CRYPTO_SHA1=y
 CONFIG_NET_FOU=y
 CONFIG_NET_FOU_IP_TUNNELS=y
 CONFIG_NETFILTER=y

tools/testing/selftests/net/netfilter/config

···
 CONFIG_CGROUP_BPF=y
 CONFIG_DUMMY=m
 CONFIG_INET_ESP=m
+CONFIG_CRYPTO_SHA1=m
 CONFIG_IP_NF_MATCH_RPFILTER=m
 CONFIG_IP6_NF_MATCH_RPFILTER=m
 CONFIG_IP_NF_IPTABLES=m