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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/Makefile

···
 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.