kernel: path and defconfig changes

Change-Id: I7003787049797a1d447313fc8edf976a5a3d9204
Disable entropy gathering for MMC device (cyanogen) and add few missing things from Andromadus' vision repo

Original commit for entropy gathering: https://github.com/Andromadus/android_device_htc_vision/commit/2ee1e727083da5908f8b45d6bcf07b7d178b4610

Change-Id: I139fc7fdfd78b40776fe0b9b3fb1a615e016d6f1
Bluetooth libbt_vncfg addition and remove goldfish blobs (@Andromadus saga repo)

Original commit: https://github.com/Andromadus/android_device_htc_saga/commit/6c3526769cfee4409fb5edc3678f2b40b121e2e7

Change-Id: I74efa9f74d929325d290b54fd613df91c40e9c63
fix prebuilt kernel ifneq

Change-Id: Idecfbc6f880187435889e29353b9c847e7514afd
comment out TARGET_KERNEL_CUSTOM_TOOLCHAIN

Change-Id: Ic290ac9b9baa8363e6f170383333e131b65716fe
(hopefully) fixed errors while compiling