So here is new firmware for Sony XPERIA P - 6.1.B.0.550. It is not Generic firmware, it is VodafoneCZ firmware. There is no change bootanimation, wallpapers etc, all same as in stock ROM, only one new Vodafone app call simply Update. I dont see any differences compare to stock 6.1.B.0.544, but try to flash and you will see. You doesnt need unlocked bootloader to flash it, just download latest FlashTool and smply flash it. If somebody want to make mirror, you can (and i will add link to this first post). Firmware is fast and stable (testing about 2 days). Enjoy
http://forum.xda-developers.com/showthread.php?t=1879290