Revert "defconfig: arm64: disable ENERGY_MODEL for kona"

This reverts commit e03ff943.
Now that the "BUG: sleeping function called from invalid context"
is fixed, enable energy model for Kona.

Change-Id: I856332a8fbd9ebd6ee31cb23ade8f05ab9f19f58
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>