linux: split overly-long dependency line for readability

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

linux/linux.mk

@@ -485,7 +485,10 @@ $(eval $(kconfig-package))
 
 # Support for rebuilding the kernel after the cpio archive has
 # been generated in $(BINARIES_DIR)/rootfs.cpio.
-$(LINUX_DIR)/.stamp_initramfs_rebuilt: $(LINUX_DIR)/.stamp_target_installed $(LINUX_DIR)/.stamp_images_installed $(BINARIES_DIR)/rootfs.cpio
+$(LINUX_DIR)/.stamp_initramfs_rebuilt: $(LINUX_DIR)/.stamp_target_installed
+$(LINUX_DIR)/.stamp_initramfs_rebuilt: $(LINUX_DIR)/.stamp_images_installed
+$(LINUX_DIR)/.stamp_initramfs_rebuilt: $(BINARIES_DIR)/rootfs.cpio
+$(LINUX_DIR)/.stamp_initramfs_rebuilt:
 	@$(call MESSAGE,"Rebuilding kernel with initramfs")
 	# Build the kernel.
 	$(LINUX_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_TARGET_NAME)