Upstream commit e4b92b108c6cd6 ("timekeeping: remove obsolete time
accessors") removed do_gettimeofday(). In Linux 4.19 this was only a
wrapper around ktime_get_real_ts64(). Use ktime_get_real_ts64() now that
the wrapper is gone to fix compilation against Linux 5.4.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>