Default [Q] Xperia U firmware upgrade HELP.!!

I flashed my Xperia U kernel using some experimental kernel.. and i got confused in middle of flashing process(I didn't implement it on my phone just flashed the kernel only. was watching a video and i only got how to flash the kernel so i did that part on my Xperia U and then left it and turned on the phone.. now it says there is an update available for your phone but i have already updated to that version.) So i want to flash my Xperia U to .89 will i be able to do it even after flashing my kernel using that experimental kernel.. Please HELP.. i am tired of new firmware notification..