msm: pcie: regiser driver using platform_driver_probe()

The msm_pcie_probe() invokes pci_common_init() which is defined as __init.
Hence use platform_driver_probe() to register the driver instead of
platform_driver_register().

Change-Id: I743c97d745b0d591a655be652c180f1376a5e716
Signed-off-by: Niranjana Vishwanathapura <nvishwan@codeaurora.org>