hw/net/i82596: Include missing 'exec/address-spaces.h' header

hw/net/i82596: Include missing 'exec/address-spaces.h' header

hw/net/i82596.c access the global 'address_space_memory'
calling the ld/st_phys() API. address_space_memory is
declared in "exec/address-spaces.h". Currently this header
is indirectly pulled in via another header. Explicitly include
it to avoid when refactoring unrelated headers:

  hw/net/i82596.c:91:23: error: use of undeclared identifier 'address_space_memory'; did you mean 'address_space_destroy'?
    return ldub_phys(&address_space_memory, addr);
                      ^~~~~~~~~~~~~~~~~~~~
                      address_space_destroy

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230619074153.44268-2-philmd@linaro.org>