staticd: Fix SRv6 SID installation and deletion

The SRv6 support in staticd (PR #16894) does not set the correct SID
parameters (block length, node length, function length).

This commit fixes the issue and computes the correct parameters.

Signed-off-by: Carmine Scarpitta <cscarpit@cisco.com>
(cherry picked from commit e1654ba)

# Conflicts:
#	staticd/static_zebra.c