bus: mhi: host: pci_generic: Remove redundant assign resource usage

Avoid redundant usage of pci_assign_resource for BAR allocation. This is
already taken care by PCI framework. Invocation of this API leads to
unnecessary relocation of BAR space to a new memory address.

Signed-off-by: Subramanian Ananthanarayanan <quic_skananth@quicinc.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
Link: https://patch.msgid.link/20250416-remove_assin_resource-v1-1-e92dd361fa0a@quicinc.com