ARM: dts: msm: add register offsets for PCIe EP mode on MDM9x40

On MDM9x40, DBI base, Slave space and PHY status registers have
different offsets from the regular offsets. Thus, add device tree
properties for these registers on MDM9x40.

Change-Id: I1dd559e911296e3804c58a83133ddc5d05b00a60
Signed-off-by: Yan He <yanhe@codeaurora.org>