arm: makefile: Moar compile optimizations
defconfig: Enable RTC for all devices (Tested on xt926)

I am leavning a msm8960_mmi_no_rtc_defconfig variant defconfig
in case xt897c has issues with this

Change-Id: Ie9b1595a808f4a12038eb96c71a6360fc259a58f
defconfig: sync with razrqcom edits