defconfig: qcs405: Enable CONFIG_NEON support for qcs405

Buildroot build, throws undefined instruction error without
proper floating point config enabled.

Enabling config neon to avoid same.

Change-Id: I727c10db8dec466e88d25f7ac50968c919b2d792
Signed-off-by: Avaneesh Kumar Dwivedi <akdwived@codeaurora.org>