time: Partially revert cleanup on msecs_to_jiffies() documentation

The documentation's intention is to compare msecs_to_jiffies() (first
sentence) with __msecs_to_jiffies() (second sentence), which is what the
original documentation did. One of the cleanups in commit f3cb8080
("time: Fix various kernel-doc problems") may have thought the paragraph
was talking about the latter since that is what it is being documented.

Thus revert that part of the change.

Fixes: f3cb8080 ("time: Fix various kernel-doc problems")
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241025110141.157205-1-ojeda@kernel.org