arm64: Kconfig: Fix merge resolution in cache options

It looks like the change to add support for ARM64_64K_PAGES
had an improper merge conflict resolution, resulting in
D-cache / I-cache disablement options being placed in the
midst of a 'choice' section. Fix that.

Change-Id: If00cf09086ca787f465196d69fa8d84a09722d3c
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>