Revert "Enable kexec-hardboot in cyanogenmod_hammerhead_defconfig"

This reverts commit 348af5e359ba0e802b00f31b0e1f82a99ee1666b.
Enable kexec-hardboot in cyanogenmod_hammerhead_defconfig

Change-Id: I9e65ce10feaf30138acce2de8b5ac623c3ec994d