flow: fix declaration after label statement

It is good to have code block that has declaration within
curly braces to avoid compilation error:
label can only be part of a statement and a declaration is not a
statement.

Signed-off-by: Gowrishankar Muthukrishnan <[email protected]>
Change-Id: I1cf0235821f7fec7149ee65bfd532233a97f631d
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/dataplane/dpu-offload/+/137993
Tested-by: sa_ip-toolkits-Jenkins <[email protected]>
Reviewed-by: Harman Kalra <[email protected]>