arm64: defconfig: holi-gki: enable qti-fixed-regulator driver

Enable the qti-fixed-regulator driver so that proxy consumer
voting may be used for fixed regulator devices.

Change-Id: I9247c31b545f7928813521010b558518e3f68b2e
Signed-off-by: Rajeev Nandan <rajeevny@codeaurora.org>