package/dropbear: rework license information

According to the LICENSE file curve25519-donna is licensed under
BSD-3-Clause license.

There is only BSD-2-Clause license mentioned so remove
BSD-2-Clause-like.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Reviewed-by: Thomas Huth <huth@tuxfamily.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/dropbear/dropbear.mk

@@ -7,7 +7,7 @@
 DROPBEAR_VERSION = 2019.78
 DROPBEAR_SITE = https://matt.ucc.asn.au/dropbear/releases
 DROPBEAR_SOURCE = dropbear-$(DROPBEAR_VERSION).tar.bz2
-DROPBEAR_LICENSE = MIT, BSD-2-Clause-like, BSD-2-Clause
+DROPBEAR_LICENSE = MIT, BSD-2-Clause, BSD-3-Clause
 DROPBEAR_LICENSE_FILES = LICENSE
 DROPBEAR_TARGET_BINS = dropbearkey dropbearconvert scp
 DROPBEAR_PROGRAMS = dropbear $(DROPBEAR_TARGET_BINS)