ARM: config: Add qcom_defconfig

Add a defconfig for mach-qcom platforms (copied from msm_defconfig).
Although these platforms are part of the multi-platform kernel, it's
useful to have a stripped down version of the defconfig that just
selects the DT based Qualcomm platforms and drivers.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>