tools/nolibc/time: drop invocation of gettimeofday system call

tools/nolibc/time: drop invocation of gettimeofday system call

This invocation uses libc types with a system call. While this works
now, upcoming changes to 'struct timeval' would require type
conversions. If types are converted anyways, the clock_gettime() based
fallback can be used everywhere, simplifying the code.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20251220-nolibc-uapi-types-v3-4-c662992f75d7@weissschuh.net