defconfig: enable zRAM

https://github.com/TeamCanjica/android_kernel_samsung_u8500/commit/dc1eefc5db62cebbc8c659ec8f84283e7016be6e
https://github.com/TeamCanjica/android_kernel_samsung_u8500/commit/226702846a0b3fec1b9af6f1e320594fddc94fb1