Print memory percentages

this gives better idea of memories used.

make.mk

@@ -62,6 +62,7 @@ CFLAGS += -MD -MP -MT $(BUILD)/$(*F).o -MF $(BUILD)/$(@F).d
 LDFLAGS += -mcpu=cortex-m0plus -mthumb
 LDFLAGS += -Wl,--gc-sections
 LDFLAGS += -Wl,--script=$(TOP)/watch-library/hardware/linker/saml22j18.ld
+LDFLAGS += -Wl,--print-memory-usage
 
 LIBS += -lm