ANDROID: fix declaration mismatch for ns_to_kernel_old_timeval

The function ns_to_kernel_old_timeval() has inconsistent declarations:

include/linux/time32.h: ns_to_kernel_old_timeval(s64 nsec);
kernel/time/time.c: ns_to_kernel_old_timeval(const s64 nsec);

This causes the ABI checks to mismatch when generated with LTO=thin

It is fixed upstream in 46dae32f ("time: Correct the prototype
of ns_to_kernel_old_timeval and ns_to_timespec64"), however, since
the android13-5.15 KMI is frozen and assumes "const s64", we can't
use the upstream fix which eliminates "const". Instead use __GENKSYMS__
to fix it for ABI generation.

Fixes: a84d1169 ("y2038: Introduce struct __kernel_old_timeval")
Signed-off-by: Todd Kjos <tkjos@google.com>
Change-Id: I43c74ae1c457607b53a08fbfb67e77f7426bcda7