defconfig: qcs405: Enable ARCH_QCS403 in qcs405 defconfig

We are trying to separate out qcs403 defconfig from qcs405.
but before we can remove support for qcs405 for 32 bit build,
we need to enable qcs403 support in qcs405 defconfig.

Change-Id: I0729d169e669a585fdcca1cd404af8a53f53022f
Signed-off-by: Avaneesh Kumar Dwivedi <akdwived@codeaurora.org>