systemd: add group sgx to udev package

>From NEWS for v250:
* Device nodes for the Software Guard eXtension enclaves (sgx_vepc) are
  now also owned by the system group "sgx".

>From NEWS for v248:
* Intel SGX enclave device nodes (which expose a security feature of
  newer Intel CPUs) will now be owned by a new system group "sgx".

Fixes following journal error entry during startup:
  /lib/udev/rules.d/50-udev-default.rules:43 Unknown group 'sgx', ignoring
This is seen already on kirkstone.

(From OE-Core rev: 3fd47697df858d4093d9cb4c6a378fc07aa4d064)

Signed-off-by: Peter Marko <peter.marko@siemens.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit bab455cd9b1b82e778f8523a767eb281edf6689e)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-selftest/files/static-group

@@ -24,3 +24,4 @@ weston-launch:x:524:
 weston:x:525:
 wayland:x:526:
 render:x:527:
+sgx:x:528:

meta/recipes-core/systemd/systemd_250.5.bb

@@ -397,7 +397,7 @@ USERADD_PACKAGES = "${PN} ${PN}-extra-utils \
                     ${@bb.utils.contains('PACKAGECONFIG', 'journal-upload', '${PN}-journal-upload', '', d)} \
 "
 GROUPADD_PARAM:${PN} = "-r systemd-journal;"
-GROUPADD_PARAM:udev = "-r render"
+GROUPADD_PARAM:udev = "-r render;-r sgx;"
 GROUPADD_PARAM:${PN} += "${@bb.utils.contains('PACKAGECONFIG', 'polkit_hostnamed_fallback', '-r systemd-hostname;', '', d)}"
 USERADD_PARAM:${PN} += "${@bb.utils.contains('PACKAGECONFIG', 'coredump', '--system -d / -M --shell /sbin/nologin systemd-coredump;', '', d)}"
 USERADD_PARAM:${PN} += "${@bb.utils.contains('PACKAGECONFIG', 'networkd', '--system -d / -M --shell /sbin/nologin systemd-network;', '', d)}"