systemd: if getty generator is disabled remove the generator, not the units

If the getty generator is disabled then it's neater to remove just the
generator tool instead of the unit files as the unit files are still
useful.

(From OE-Core rev: 2beb3170af6ebf3a6fff6953a2d48f70f61b959f)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/systemd/systemd_257.3.bb

@@ -287,9 +287,11 @@ do_install() {
 		fi
 	fi
 	install -d ${D}/${base_sbindir}
-	if ${@bb.utils.contains('PACKAGECONFIG', 'serial-getty-generator', 'false', 'true', d)}; then
-		# Provided by a separate recipe
-		rm ${D}${systemd_system_unitdir}/serial-getty* -f
+
+	if ! ${@bb.utils.contains('PACKAGECONFIG', 'serial-getty-generator', 'true', 'false', d)}; then
+		# Remove the serial-getty generator and instead use explicit services
+		# created by the systemd-serialgetty recipe
+		find ${D} -name \*getty-generator\* -delete
 	fi
 
 	# Provide support for initramfs