Staging: dgnc: Remove unused sniff code

The output written by dgnc_sniff_nowait_nolock() is never used
anywhere since commit 35cf9045 ("staging: dgnc: removes proc code")
deleted the code that used to copy it to user space.
dgnc_sniff_nowait_nolock() uses 'timeval' to create header timestamps for
the data dump.

32-bit systems using 'struct timeval' will break in the year 2038,
This patch removes dgnc_sniff_nowait_nolock() and all ch_sniff_* members
of struct channel_t defined in "dgnc_driver.h". It also removes their usage
from the driver files and hence y2038 issue is also resolved.

Signed-off-by: Somya Anand <somyaanand214@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>