ARM: dts: msm: Update boot option for PCIe on APQ8098

Few PCIe clients does not have option to call for enumeration.
Update boot option for PCIe such that enumeration is done as
part of PCIe RC probe.

Change-Id: I1bb977b7e21c046ee7757ed509762897e2bcdd8d
Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>