ARM: OMAP2+: drop hwmod-clock helper comment

Since commit a4f6cdb0 ("ARM: OMAP: omap_device: Add
omap_device_[alloc|delete] for DT integration"),
_add_hwmod_clocks_clkdev() is called from omap_device_alloc().

Drop the outdated comment referring to how this function was used ten
odd years ago.

Signed-off-by: Johan Hovold <johan@kernel.org>
Message-Id: <20220303180014.2639-3-johan@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>