pimd: reject inconsistent address/mask "ip pim rp command"

pimd: reject inconsistent address/mask "ip pim rp command"

Issue: Configure "ip pim rp x.x.x.x 225.0.0.0/4".
Show running config shows "ip pim rp x.x.x.x 224.0.0.0/4"
This is mis-leading.

Root-cause: Internally 225.0.0.0/4 is getting converted to
224.0.0.0/4 group mask, since the prefix length is 4.

Fix: Restrict the user to configure inconsistent group address
mask by throughing a cli error "Inconsistent address and mask".

Signed-off-by: Sarita Patra <saritap@vmware.com>