cypress-touchkey: attempt to filter out "phantom" key-presses

ariesve is affected by this problem, this workaround is based on:
https://github.com/CyanogenMod/android_kernel_samsung_aries/commit/4afad77c61c7cb54cce293034cdb07a928f22d20

https://github.com/CyanogenMod/android_kernel_samsung_aries/commit/cb8fa22cba177709848321e8100ee60ee1684530