Hexagon (target/hexagon) Move pkt_has_store_s1 to DisasContext

The pkt_has_store_s1 field is only used for bookkeeping helpers with
a load.  With recent changes that eliminate the need to free TCGv
variables, it makes more sense to make this transient.

These helpers already take the instruction slot as an argument.  We
combine the slot and pkt_has_store_s1 into a single argument called
slotval.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230427230012.3800327-21-tsimpson@quicinc.com>