msm8974: Reserve memory for ramconsole

 * Samsung's implementation of ramconsole depends on the device
   being at DEBUG_LEVEL_HIGH, which makes collecting crash logs
   from devices in the wild impossible.
 * Enable the standard ramconsole by reserving persistent ram.

Change-Id: If59e08be09db7ebba97e4dc66f2167395032d807

Conflicts:
	arch/arm/configs/msm8974_sec_defconfig
msm8974: ..and update the devicetree

Change-Id: I2c0be98b75917069def0c3f11f2d2f206b0cac08

Conflicts:
	arch/arm/boot/dts/msm8974/msm8974-sec.dtsi
android: ram_console: convert to use device tree