staging: media: lirc: Delete unused function tv2int

The function tv2int is used to convert timeval to int.

32-bit systems using 'struct timeval' will break in the year 2038,
so we have to replace that code with more appropriate types.
This patch changes the lirc_imon.c file of media: lirc driver.

tv2int function is static and not used anywhere in this file too,
so it is removed. I also build tested it.

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>