stm32l4: crc-v2: enable common code

Possible now that the v2 unification code has landed.

lib/stm32/l4/Makefile

@@ -44,6 +44,7 @@ OBJS		= adc.o flash.o pwr.o rcc.o
 OBJS            += rcc_common_all.o
 OBJS            += gpio_common_all.o gpio_common_f0234.o
 OBJS            += adc_common_v2.o adc_common_v2_multi.o
+OBJS            += crc_common_all.o crc_v2.o
 OBJS            += rng_common_v1.o
 OBJS            += timer_common_all.o
 OBJS            += i2c_common_v2.o