bnxt: fix bnxt_hwrm_fw_set_time for y2038

On 32-bit architectures, rtc_time_to_tm() returns incorrect results
in 2038 or later, and do_gettimeofday() is broken for the same reason.

This changes the code to use ktime_get_real_seconds() and time64_to_tm()
instead, both of them are 2038-safe, and we can also get rid of the
CONFIG_RTC_LIB dependency that way.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>