clocksource: Remove unnecessary strscpy() size argument

The size argument of strscpy() is only required when the destination
pointer is not a fixed sized array or when the copy needs to be smaller
than the size of the fixed sized destination array.

For fixed sized destination arrays and full copies, strscpy() automatically
determines the length of the destination buffer if the size argument is
omitted.

This makes the explicit sizeof() unnecessary. Remove it.

[ tglx: Massaged change log ]

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250311110624.495718-2-thorsten.blum@linux.dev