ARM: dts: Document guidelines for DCS command timeout issue

Document the guidelines for changing dtsi file for timeout issue
of DCS short packets in LP mode, when video mode is enabled.

Change-Id: Iab4baa74c936e36b2c6b16aad9e3a4f20bdad838
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>