[make] add ability to set EXTRA_LINKER_SCRIPTS in modules

This allows for individual modules to extend the main linker script,
primarily to add their own sections to interate over.
Remove the main shared_* linker scripts.

dev/rules.mk

@@ -12,4 +12,6 @@ MODULE_SRCS += \
 	$(LOCAL_DIR)/class/fb_api.c \
 	$(LOCAL_DIR)/class/netif_api.c \
 
+EXTRA_LINKER_SCRIPTS += $(LOCAL_DIR)/devices.ld $(LOCAL_DIR)/drivers.ld
+
 include make/module.mk