dropbear: bump version to 2016.74

According to https://matt.ucc.asn.au/dropbear/CHANGES there were some
severe security issues fixed.

Signed-off-by: Alexander Dahl <post@lespocky.de>
Acked-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/dropbear/dropbear.hash

@@ -1,2 +1,2 @@
 # From https://matt.ucc.asn.au/dropbear/releases/SHA256SUM.asc
-sha256	5c61a4f69b093b688629cd365be38701485ff63cfb23642dab7a05ad250aefd7  dropbear-2016.73.tar.bz2
+sha256 2720ea54ed009af812701bcc290a2a601d5c107d12993e5d92c0f5f81f718891 dropbear-2016.74.tar.bz2

package/dropbear/dropbear.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-DROPBEAR_VERSION = 2016.73
+DROPBEAR_VERSION = 2016.74
 DROPBEAR_SITE = http://matt.ucc.asn.au/dropbear/releases
 DROPBEAR_SOURCE = dropbear-$(DROPBEAR_VERSION).tar.bz2
 DROPBEAR_LICENSE = MIT, BSD-2c-like, BSD-2c