stm32:l0: Correctly compile as m0+, not m0.

Committed to binutils back in 2012, so even though it has no real impact, it at
least does the right thing for future compilers to make better decisions.

Signed-off-by: Karl Palsson <karlp@tweak.net.au>

lib/stm32/l0/Makefile

@@ -29,7 +29,7 @@ CFLAGS		= -Os -g \
 		  -Wredundant-decls -Wmissing-prototypes -Wstrict-prototypes \
 		  -Wundef -Wshadow \
 		  -I../../../include -fno-common \
-		  -mcpu=cortex-m0 $(FP_FLAGS) -mthumb -Wstrict-prototypes \
+		  -mcpu=cortex-m0plus $(FP_FLAGS) -mthumb -Wstrict-prototypes \
 		  -ffunction-sections -fdata-sections -MD -DSTM32L0
 
 ARFLAGS		= rcs