lib: in routemap.c if using a switch for an enum get rid of enum

lib: in routemap.c if using a switch for an enum get rid of enum

From looking at a current PR: #4297, we see that routemap.c code
was not properly updating dependency information for some
route_map_event_t enum types.  This has lead to dependancy
information not being updated properly.  While at this time
I do not know whether or not we need to update the switch
for the missing types, I do know that if we add something in
the future we should make the person adding the code consider
this.  So let's remove all `default:` switch statement handlers
from routemap.c when switching on an enum.  Future time will
need to be spent to figure out what is needed to be done here.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>