rtc: Rename lib_test to test_rtc_lib

When compiling the RTC library functions test as a module, the module
has the non-descriptive name "lib_test.ko".  Fix this by renaming it to
"test_rtc_lib.ko".

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/47019d7f8ced12107b54a372fdf34b1b8f7b6183.1751355848.git.geert@linux-m68k.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: geertu

drivers/rtc/Makefile

@@ -15,7 +15,7 @@ rtc-core-$(CONFIG_RTC_INTF_DEV)		+= dev.o
 rtc-core-$(CONFIG_RTC_INTF_PROC)	+= proc.o
 rtc-core-$(CONFIG_RTC_INTF_SYSFS)	+= sysfs.o
 
-obj-$(CONFIG_RTC_LIB_KUNIT_TEST)	+= lib_test.o
+obj-$(CONFIG_RTC_LIB_KUNIT_TEST)	+= test_rtc_lib.o
 
 # Keep the list ordered.