dhcpdump: Fix patch file name

Use the naming convention for patches, which is:

	<packagename>-<number>-<description>.patch

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

diff --git a/package/dhcpdump/dhcpdump-1.8-use-non-bsd-structures.patch b/package/dhcpdump/dhcpdump-0001-use-non-bsd-structures.patch
similarity index 100%
rename from package/dhcpdump/dhcpdump-1.8-use-non-bsd-structures.patch
rename to package/dhcpdump/dhcpdump-0001-use-non-bsd-structures.patch