Fixed ramdisk size setup

For setting up the brd rd_size option kiwi creates
99-brd.conf used at load time of the kernel brd driver.
The location for the conf file is set to /etc/modprobe.d/
However, in newer versions the location has changed to
/usr/lib/modprobe.d/ and /etc/modprobe.d is no longer
expected to exist. This commit makes sure /etc/modprobe.d
is created if not present.

dracut/modules.d/90kiwi-dump/kiwi-dump-image.sh

@@ -50,6 +50,7 @@ function get_disk_list {
         local rd_size
         local modfile=/etc/modprobe.d/99-brd.conf
         rd_size=$(getarg ramdisk_size=)
+        mkdir -p /etc/modprobe.d
         if [ -n "${rd_size}" ];then
             echo "options brd rd_size=${rd_size}" > ${modfile}
         fi