arm64: defconfig: Clean the lines for unset CONFIGs

The CONFIGS, CONFIG_RPMSG_QCOM_GLINK_SMEM, CONFIG_RPMSG_QCOM_SMD,
and CONFIG_QCOM_SMP2P_SLEEPSTATE are not needed and can be removed
to avoid defconfig-merge warnings. They can be set later if required.

Change-Id: Ia3fe128525c561f8d187ae451f508a685a9ab2cf
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>