zebra, bgpd: Fixup MULTIPATH_NUM usage to not consider 0

The code has spots where MULTIPATH_NUM set to 0 is equal to 64.
Now that MULTIPATH_NUM is set from the makefile to never be 0,
remove the code that depends on this.

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