defconfig: arm64: msm: disable dummy regulator support

Dummy regulator was added initially for simulator bring-up.
As PMIC regulator support is in place remove dummy regulator
from kernel configuration.

Change-Id: Ie1305712d09f8d85bcdc62cc00ef9eb197de9cc3
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>