ARM: dts: msm: Add common CMA device configuration for msm8909w & apq8909

TZ expects firmware regions under 512MB. BG firmware region is
allocated from common CMA region. Add common CMA configuration
and restrict it within 512MB region for msm8909w and apq8009.

Change-Id: I9785470c15bb4d4f4fad74b40eb01c1d4f36edba
Signed-off-by: Vishwanath Raju K <vishk@codeaurora.org>