hw/arm/aspeed_ast27x0-ssp: Change to use Aspeed27x0CoprocessorState

hw/arm/aspeed_ast27x0-ssp: Change to use Aspeed27x0CoprocessorState

Refactor the AST27x0 SSP implementation to use the unified
Aspeed27x0CoprocessorState structure shared between SSP and TSP.
Previously, SSP and TSP each defined separate state structures
(Aspeed27x0SSPSoCState and Aspeed27x0TSPSoCState), which contained
identical members and caused unnecessary code duplication.

This change removes Aspeed27x0SSPSoCState and replaces it with
Aspeed27x0CoprocessorState, consolidating shared coprocessor state fields
into a single definition in aspeed_coprocessor.h.

This refactor unifies SSP and TSP under the same coprocessor state type,
improving code maintainability and consistency across Aspeed coprocessor
implementations.

No functional change.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20251013054334.955331-13-jamin_lin@aspeedtech.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>