Remove superfluous preprocessor conditionals from LM73 driver

(1) Remove unused symbol "CFG_EEPROM_PAGE_WRITE_ENABLE".

(2) Use conditional Makefile.o.

Signed-off-by: Larry Johnson <lrj@acm.org>
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 32e3f44..065433a 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -34,7 +34,7 @@
 COBJS-y += ds1621.o
 COBJS-y += ds1722.o
 COBJS-y += ds1775.o
-COBJS-y += lm73.o
+COBJS-$(CONFIG_DTT_LM73) += lm73.o
 COBJS-y += lm75.o
 COBJS-y += lm81.o