drivers: staging: dgnc: Replace min with min_t

This patch replaces min with min_t and eliminates
the following warning found by checkpatch.pl:

WARNING: min() should probably be min_t(uint, n, 12)

Signed-off-by: Darshana Padmadas <darshanapadmadas@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>