PCI: dwc: Simplify config space handling

PCI: dwc: Simplify config space handling

The config space is divided in half for type 0 and type 1 accesses, but
this is pointless as there's only one iATU window which is
reconfigured on each access.

The only platform doing something custom is TI Keystone (surprise!).
It does its own mapping of the config space to avoid spliting the
config space and never actually uses va_cfg1_base as it has its own
config space accessors. With the splitting removed, Keystone can use the
default mapping of config space.

Link: https://lore.kernel.org/r/20200821035420.380495-20-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Murali Karicheri <m-karicheri2@ti.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Gustavo Pimentel <gustavo.pimentel@synopsys.com>