sysmocom-idu: remove ifplugd from MACHINE_ESSENTIAL_EXTRA_RDEPENDS

[hfreyther: I asked henning to move forward and not test this. We
do not have dhcp/dynamic config in /etc/network/interfaces and the
link will always be up on the idu due it being connected to a switch.
ifplugd is not doing anything useful in this context]

Fixes: SYS#1535

conf/machine/sysmocom-idu.conf

@@ -33,7 +33,6 @@ GLIBC_ADDONS = "nptl"
 GLIBC_EXTRA_OECONF = "--with-tls"
 
 #MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "v86d"
-MACHINE_ESSENTIAL_EXTRA_RDEPENDS = "\
-	busybox-ifplugd linux-firmware-rtl-nic "
+MACHINE_ESSENTIAL_EXTRA_RDEPENDS = "linux-firmware-rtl-nic"
 
 MACHINEOVERRIDES = "${MACHINE}:sysmocom-bsc"