initrd: remove the now superfluous sentinel element from ctl_table array

initrd: remove the now superfluous sentinel element from ctl_table array

This commit comes at the tail end of a greater effort to remove the empty
elements at the end of the ctl_table arrays (sentinels) which will reduce
the overall build time size of the kernel and run time memory bloat by ~64
bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel from kern_do_mounts_initrd_table.

Link: https://lkml.kernel.org/r/20240328-jag-sysctl_remset_misc-v1-4-47c1463b3af2@samsung.com
Signed-off-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>