[eNb] Undefined behavior of defining two global enb_properties.

In enb_config.h a global variable is defined at line 293:

Enb_properties_array_t enb_properties;

However, a same global variable with the same name is defined in oaisim_functions.c at line 185:

const Enb_properties_array_t *enb_properties;

These two global variables with the same name but different type, which is undefined behaviour. A quick solution is to change the linkage of enb_properties in enb_config.h to static as it can still be accessed through enb_config_get(void) function.