Fix refresh rate on sony-amami
See https://github.com/postmarketOS/pmbootstrap/wiki/sony-amami-(Xperia-Z1-Compact)#issues
Makes weston fall back to default refresh rate (60 Hz).
I know this is an awful hack, but I don't think this kernel/driver worth the time debugging, since the panel driver could easily be ported to mainline based on robclark's work.