V4L/DVB (11060): au8522: rename the au8522.c source file

Rename the au8522.c file to au8522_dig.c so that more source files can be
added to the driver while preserving the original name of au8522.ko

Thanks to Michael Krufky <mkrufky@linuxtv.org> and Steven Toth
<stoth@linuxtv.org> for providing sample hardware, engineering level support,
and testing.
Signed-off-by: Devin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/Makefile

@@ -8,6 +8,7 @@ EXTRA_CFLAGS += -Idrivers/media/common/tuners/
 s921-objs := s921_module.o s921_core.o
 stb0899-objs = stb0899_drv.o stb0899_algo.o
 stv0900-objs = stv0900_core.o stv0900_sw.o
+au8522-objs = au8522_dig.o
 
 obj-$(CONFIG_DVB_PLL) += dvb-pll.o
 obj-$(CONFIG_DVB_STV0299) += stv0299.o