Zero-width hwpe_sel_o when NB_HWPES=1 (unguarded $clog2 in port range) #102

Summary:
The output port hwpe_sel_o is declared with a width derived from $clog2(NB_HWPES). When NB_HWPES == 1, $clog2(1) == 0, so the packed range becomes [-1:0], causing compilation/elaboration errors. This issue follows pulp-platform/cluster_peripherals#8 (comment)

Affected code:

Possible fix:
output logic [((NB_HWPES>1)?$clog2(NB_HWPES):1)-1:0] hwpe_sel_o

Checklist:

• Replace [$clog2(NB_HWPES)-1:0] occurrences
• Add and assert (NB_HWPES >= 1).
• Verify builds for NB_HWPES for {1, 2, 3, 8, …}.