tgt: Update init script

This replaces the use of uci_validate_section() with
uci_load_validate(), which removes the need to declare local variables
for every config option.

This also adds a service_triggers() function, removes a duplicate
option, and removes some unnecessary curly brackets.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

net/tgt/Makefile

@@ -8,7 +8,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=tgt
 PKG_VERSION:=1.0.74
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://codeload.github.com/fujita/tgt/tar.gz/v$(PKG_VERSION)?