ARM: dts: msm: reserve memory for early-audio on msm8996

Reserving memory for early-audio. The memory is used as a buffer to
store PCM data for the LPASS DMA to read for playback while the
kernel is booting.

Change-Id: I6ec3b1f549da71d026b77508f2c56d88487eff9b
Signed-off-by: Honghao Liu <honghaol@codeaurora.org>