SW: move from ntp/ntpdate to ntpsec/ntpsec-ntpdate in GRML_SMALL + GRML_FULL

SW: move from ntp/ntpdate to ntpsec/ntpsec-ntpdate in GRML_SMALL + GRML_FULL

Starting with bookworm (current Debian/testing), ntpsec replaces ntp,
and ntpsec-ntpdate replaces ntpdate. Now both the ntp + ntpdate packages
are transitional packages. Given that ntpsec/ntpsec-ntpdate are
available even for oldstable, let's follow this transition now (also see
https://sources.debian.org/src/ntpsec/1.2.1%2Bdfsg1-6/debian/NEWS/).

FTR, as of 2022-04-11:

| % rmadison ntpsec ntpsec-ntpdate
| ntpsec         | 1.1.3+dfsg1-2+deb10u1 | oldstable              | source, amd64, arm64, armel, armhf, i386, mips, mips64el, mipsel, ppc64el, s390x
| ntpsec         | 1.1.3+dfsg1-2+deb10u1 | oldstable-debug        | source
| ntpsec         | 1.2.0+dfsg1-4~bpo10+1 | buster-backports       | source, amd64, arm64, armel, armhf, i386, mips, mips64el, mipsel, ppc64el, s390x
| ntpsec         | 1.2.0+dfsg1-4~bpo10+1 | buster-backports-debug | source
| ntpsec         | 1.2.0+dfsg1-4         | stable                 | source, amd64, arm64, armel, armhf, i386, mips64el, mipsel, ppc64el, s390x
| ntpsec         | 1.2.1+dfsg1-6         | testing                | source, amd64, arm64, armel, armhf, i386, mips64el, mipsel, ppc64el, s390x
| ntpsec         | 1.2.1+dfsg1-6         | unstable               | source, amd64, arm64, armel, armhf, i386, mips64el, mipsel, ppc64el, s390x
| ntpsec         | 1.2.1+dfsg1-6         | unstable-debug         | source
| ntpsec-ntpdate | 1.1.3+dfsg1-2+deb10u1 | oldstable              | amd64, arm64, armel, armhf, i386, mips, mips64el, mipsel, ppc64el, s390x
| ntpsec-ntpdate | 1.2.0+dfsg1-4~bpo10+1 | buster-backports       | amd64, arm64, armel, armhf, i386, mips, mips64el, mipsel, ppc64el, s390x
| ntpsec-ntpdate | 1.2.0+dfsg1-4         | stable                 | amd64, arm64, armel, armhf, i386, mips64el, mipsel, ppc64el, s390x
| ntpsec-ntpdate | 1.2.1+dfsg1-6         | testing                | amd64, arm64, armel, armhf, i386, mips64el, mipsel, ppc64el, s390x
| ntpsec-ntpdate | 1.2.1+dfsg1-6         | unstable               | amd64, arm64, armel, armhf, i386, mips64el, mipsel, ppc64el, s390x