selftests: net: Explicitly enable CONFIG_CRYPTO_SHA1 for IPsec

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 <pabeni@redhat.com>
Closes: https://lore.kernel.org/r/766e4508-aaba-4cdc-92b4-e116e52ae13b@redhat.com
Suggested-by: Florian Westphal <fw@strlen.de>
Acked-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20250818205426.30222-2-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>