package/linux-tools: gpio does not build in parallel

Partially fixes #10276.

Reported-by: Ciro Santilli <ciro.santilli@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Ciro Santilli <ciro.santilli@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/linux-tools/linux-tool-gpio.mk.in

@@ -15,13 +15,13 @@ define GPIO_BUILD_CMDS
 		exit 1 ; \
 	fi
 
-	$(TARGET_MAKE_ENV) $(MAKE) -C $(LINUX_DIR)/tools \
+	$(TARGET_MAKE_ENV) $(MAKE1) -C $(LINUX_DIR)/tools \
 		$(GPIO_MAKE_OPTS) \
 		gpio
 endef
 
 define GPIO_INSTALL_TARGET_CMDS
-	$(TARGET_MAKE_ENV) $(MAKE) -C $(LINUX_DIR)/tools \
+	$(TARGET_MAKE_ENV) $(MAKE1) -C $(LINUX_DIR)/tools \
 		$(GPIO_MAKE_OPTS) \
 		DESTDIR=$(TARGET_DIR) \
 		gpio_install