firewire: obsolete usage of *-objs in Makefile for KUnit test

Nowadays *-objs list is just for user space programs.

This commit obsolete the usage, and simplify Makefile for firewire KUnit
tests since the tests are not composite objects.

Link: https://lore.kernel.org/r/20240508105351.532693-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

drivers/firewire/Makefile

@@ -16,8 +16,5 @@ obj-$(CONFIG_FIREWIRE_NET)  += firewire-net.o
 obj-$(CONFIG_FIREWIRE_NOSY) += nosy.o
 obj-$(CONFIG_PROVIDE_OHCI1394_DMA_INIT) += init_ohci1394_dma.o
 
-firewire-uapi-test-objs += uapi-test.o
-firewire-packet-serdes-test-objs += packet-serdes-test.o
-
-obj-$(CONFIG_FIREWIRE_KUNIT_UAPI_TEST) += firewire-uapi-test.o
-obj-$(CONFIG_FIREWIRE_KUNIT_PACKET_SERDES_TEST) += firewire-packet-serdes-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_UAPI_TEST) += uapi-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_PACKET_SERDES_TEST) += packet-serdes-test.o