diag: Support dynamic switch between USB and PCIe interface

Add support to configure PCIe or USB interface during boot based on
PCIE config definition. Support to dynamic switch between USB and
PCIe by existing IOCTL is added.

Change-Id: I9a51ea5dd6c9d370c7aa0419e9772067f16e9ab6
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>