[wookey] skip proof flash_mass_erase, whose code is not handled by WP

case_studies/wookey/loader/GNUmakefile

@@ -75,7 +75,13 @@ $(MAIN_TARGET).parse: $(SRCS)
 # use path.mk if you want to change the default here
 CORES ?= 1
 WP_CUSTOM ?=
-WP_FLAGS= -wp-par $(CORES) -wp-timeout 20 -wp-no-warn-memory-model -wp-cache update $(WP_CUSTOM)
+WP_FLAGS=\
+ -wp-par $(CORES) \
+ -wp-timeout 20 \
+ -wp-no-warn-memory-model \
+ -wp-cache update \
+ -wp-skip-fct flash_mass_erase \
+ $(WP_CUSTOM)
 
 META_FLAGS= #-meta-keep-proof-files