52-dracut.install: fix error on remove

Closes: https://bugs.gentoo.org/961529
Signed-off-by: Nowa Ammerlaan <[email protected]>

Author: Nowa-Ammerlaan

hooks/systemd/52-dracut.install

@@ -3,8 +3,8 @@
 COMMAND=${1:?}
 KERNEL_VERSION=${2:?}
 #shellcheck disable=SC2034
-BOOT_DIR_ABS=${3:?}
-KERNEL_IMAGE=${4:?}
+BOOT_DIR_ABS=${3}
+KERNEL_IMAGE=${4}
 
 # If the initrd was provided on the kernel command line, we shouldn't generate our own.
 if [[ "${COMMAND}" != "add" || "${#}" -gt 4 ]]; then