You can edit the defconfig files with an editor. The defconfig you need to edit is arch/arm/configs/cyanogenmod_hammerhead_defconfig.
Just enable the modules support(CONFIG_MODULES=y) and try again.

EDIT:
Maybe you need to do a 'make clean' before your next compile try.
Or copy your modified defconfig file to .config in your kernel/lge/hammerhead directory or do a 'make cyanogenmod_hammerhead_defconfig' before doing make hybris-hal.