PM: hibernate: Remove size arguments when calling strscpy()

The size parameter is optional and strscpy() automatically determines
the length of the destination buffer using sizeof() if the argument is
omitted. This makes the explicit sizeof() calls unnecessary. Remove
them to shorten and simplify the code.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://patch.msgid.link/20250318080755.61126-2-thorsten.blum@linux.dev


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>