ARM: qcom_defconfig: enable RPMSG_QCOM_SMD

As of commit 5052de8d, QCOM_SMD_RPM and various other config
options enabled in the qcom_defconfig depends on the RPMSG. If
QCOM_SMD_RPM config option is not selected it disables the
REGULATOR_QCOM_SMD_RPM and other essential config options.

Signed-off-by: Bhushan Shah <bshah@kde.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>