[media] dvb-frontend: Replace timeval with ktime_t

struct timeval uses a 32-bit seconds representation which will
overflow in the year 2038 and beyond. This patch replaces
the usage of struct timeval with ktime_t which is a 64-bit
timestamp and is year 2038 safe.
This patch is part of a larger attempt to remove all instances
of 32-bit timekeeping variables (timeval, timespec, time_t)
which are not year 2038 safe, from the kernel.

[mchehab@osg.samsung.com: add a missing parenthesis, breaking compilation]
Suggested-by: Arnd Bergmann <arndb@arndb.de>
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>