HONG KONG, Oct 25 (Reuters) - Hong Kong's efforts to revive its shrinking stock market are mere stopgap solutions, as analysts say a reversal in fortunes for Asia's premier financial hub would not be possible without a major improvement in China's economic prospects. Hong Kong's government has for months tried to boost turnover and revive a torpid stock market, the latest coming on Wednesday when its leader John Lee announced an immigration plan tied to investments and a cut in the stamp duty on stock trades. But the region's key financial centre and gateway to the world's second largest economy...