ubus: update to the latest version

Adds the following fixes:

91acde6 libubus: do not modify uloop_cancelled
763b9b2 libubus: reset ctx->sock.eof to fix reconnect issues

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/system/ubus/Makefile

@@ -5,9 +5,9 @@ PKG_RELEASE:=1
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=$(LEDE_GIT)/project/ubus.git
-PKG_SOURCE_DATE:=2017-01-22
-PKG_SOURCE_VERSION:=6f4e11e1db399074273944329883f9c35e7daef6
-PKG_MIRROR_HASH:=4b80cf4ff8fa0e103d6626014404c031a9e886b8fbc422fb65a9c36b3b787585
+PKG_SOURCE_DATE:=2017-02-03
+PKG_SOURCE_VERSION:=91acde66b963e238aba35fb4f2030a147df84cd4
+PKG_MIRROR_HASH:=47077163f74469e8baf6aa4dc10edc32a75f6609a1cef1d1201f091b7aec42cf
 CMAKE_INSTALL:=1
 
 PKG_LICENSE:=LGPL-2.1