Move assertion statement outside of `always_comb` block

Created by: ricted98

The assertion included in the always_comb block apparently violates the requirements in section 9.2.2.2.2 of the SystemVerilog standard:

Statements in an always_comb shall not include those that block, have blocking timing or event controls, or fork-join statements.

My compilation flow uses Synopsis vlogan. Namely, the reported error is:

Error-[SV-BCACF] Blocking construct in always_comb/ff

tag_cmp Statements in an always_comb shall not include those that block, have blocking timing or event controls, or forkjoin statements. The always_ff procedure imposes the restriction that it contains one and only one event control and no blocking timing controls. Try using simple always blocks.