msm: pcie: Fix the Root Port class code early during device configuration

Currently, the Root Port class code is fixed in header fixup stage.
This is causing the PCIE framework to throw an error message.
Move fixing the Root Port class code to early fixup stage.

Change-Id: Ie37ed555e9602d8441961c44b48e69f8b9daf6e5
Signed-off-by: Niranjana Vishwanathapura <nvishwan@codeaurora.org>