for --init-rpl-role.

Problem: There are two variables involved in this issue,
rpl_status and rpl_role_type. The former is an array containing
the description of the possible values for the latter.

rpl_status is declared as an enumeration and is stored in a 4
bytes integer. On the other hand, my_getopt, reads enum values
into a ulong:

  *(ulong*)value= arg;

This is overwriting the memory used for rpl_role_type, 
corrupting the first entry in the array.

Fix: We fix this by re-declaring rpl_status as a ulong, so that it
has space to accommodate the value "parsed" in my_getopt .