dev: Adding support for large BAR

dev: Adding support for large BAR

During PCI setup, this patch checks if a Base Address Register (BAR) is
used as a large BAR (64 bits rather than 32), and return proper address
range. The order which updates are done is decided by kernel, so this
patch implements both cases (writing lower or upper bits first).

Bit 2 in a BAR indicates a 64-bit decoder (10X to be more exact, 11X is
reserved).

The addresses in BARAddrs are full addresses and are set to zero for BAR
providing upper 32 bits to avoid conflicts in addr ranges reported.

Change-Id: I93303d36ac83dab9ed6837c81e77c9dfb778f409
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22082
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>