tools: gpio: Correctly add make dependencies for gpio_utils

gpio tools fail to build correctly with make parallelization:

$ make -s -j24
ld: gpio-utils.o: file not recognized: file truncated
make[1]: *** [/home/labbott/linux_upstream/tools/build/Makefile.build:145: lsgpio-in.o] Error 1
make: *** [Makefile:43: lsgpio-in.o] Error 2
make: *** Waiting for unfinished jobs....

This is because gpio-utils.o is used across multiple targets.
Fix this by making gpio-utios.o a proper dependency.

Cc: <stable@vger.kernel.org>
Signed-off-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

tools/gpio/Build

+gpio-utils-y += gpio-utils.o
 lsgpio-y += lsgpio.o gpio-utils.o
 gpio-hammer-y += gpio-hammer.o gpio-utils.o
 gpio-event-mon-y += gpio-event-mon.o gpio-utils.o

tools/gpio/Makefile

@@ -35,11 +35,15 @@ $(OUTPUT)include/linux/gpio.h: ../../include/uapi/linux/gpio.h
 
 prepare: $(OUTPUT)include/linux/gpio.h
 
+GPIO_UTILS_IN := $(output)gpio-utils-in.o
+$(GPIO_UTILS_IN): prepare FORCE
+	$(Q)$(MAKE) $(build)=gpio-utils
+
 #
 # lsgpio
 #
 LSGPIO_IN := $(OUTPUT)lsgpio-in.o
-$(LSGPIO_IN): prepare FORCE
+$(LSGPIO_IN): prepare FORCE $(OUTPUT)gpio-utils-in.o
 	$(Q)$(MAKE) $(build)=lsgpio
 $(OUTPUT)lsgpio: $(LSGPIO_IN)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
@@ -48,7 +52,7 @@ $(OUTPUT)lsgpio: $(LSGPIO_IN)
 # gpio-hammer
 #
 GPIO_HAMMER_IN := $(OUTPUT)gpio-hammer-in.o
-$(GPIO_HAMMER_IN): prepare FORCE
+$(GPIO_HAMMER_IN): prepare FORCE $(OUTPUT)gpio-utils-in.o
 	$(Q)$(MAKE) $(build)=gpio-hammer
 $(OUTPUT)gpio-hammer: $(GPIO_HAMMER_IN)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@
@@ -57,7 +61,7 @@ $(OUTPUT)gpio-hammer: $(GPIO_HAMMER_IN)
 # gpio-event-mon
 #
 GPIO_EVENT_MON_IN := $(OUTPUT)gpio-event-mon-in.o
-$(GPIO_EVENT_MON_IN): prepare FORCE
+$(GPIO_EVENT_MON_IN): prepare FORCE $(OUTPUT)gpio-utils-in.o
 	$(Q)$(MAKE) $(build)=gpio-event-mon
 $(OUTPUT)gpio-event-mon: $(GPIO_EVENT_MON_IN)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@