mkosi-initrd: Apply cryptsetup creds to all instances of systemd-cryptsetup@.service

This follows the suggestion made in https://github.com/systemd/systemd/pull/30309
to apply "cryptsetup.*" credentials to all instances of
systemd-cryptsetup@.service instead of only to
systemd-cryptsetup@root.service.

diff --git a/mkosi-initrd/mkosi.extra/usr/lib/systemd/system/systemd-cryptsetup@root.service.d/credential.conf b/mkosi-initrd/mkosi.extra/usr/lib/systemd/system/systemd-cryptsetup@.service.d/credential.conf
similarity index 100%
rename from mkosi-initrd/mkosi.extra/usr/lib/systemd/system/systemd-cryptsetup@root.service.d/credential.conf
rename to mkosi-initrd/mkosi.extra/usr/lib/systemd/system/systemd-cryptsetup@.service.d/credential.conf