[media] rc-core: Remove 'struct timeval' usage

streamzap uses 'struct timeval' to store the start time of a signal for
gap tracking. struct timeval uses a 32-bit seconds representation which
will overflow in year 2038 and beyond. Replace struct timeval with ktime_t
which uses a 64-bit seconds representation and is 2038 safe. This patch
uses ktime_get_real() preserving the use of wall-clock time in the
original code.

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>