Increase rfm12_ask sync time in rfm12_ask_2272_1527_send

Current short delay time leads to instable switching behaviour for 2272 based radio switchable outlets.
Harald Roelle analysed the problem ([ethersex-devel] RFM12 ASK, Instabiles Schaltverhalten inkl. mögl. Lösung): The current sync time is more alike the signal send by the remote controls.