providers/implementations/keymgmt/ecx_kmgmt.c.in: remove PCT on ECX import

providers/implementations/keymgmt/ecx_kmgmt.c.in: remove PCT on ECX import

While PCT on import has been removed for DH, EC, RSA, and SLH-DSA,
ECX seems to be overlooked.  Correct that omission.

Complements: 7f7f75816f26 "import pct: remove import PCTs for most algorithms"
Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28573)

(cherry picked from commit 05d12fdd955d4cb3efc769becc3d5ceb9a322fdc)