PCI: endpoint: Clear BAR before freeing its space

Associated pci_epf_bar structure is needed in pci_epc_clear_bar() to
clear a BAR correctly but it is reset in pci_epf_free_space() (that
is called first) which results in pci_epc_clear_bar() failure.

Reorder the pci_epc_clear_bar()/pci_epf_free_space() calls execution
to fix the issue.

Signed-off-by: Alan Mikhak <alan.mikhak@sifive.com>
[lorenzo.pieralisi@arm.com: reworded the commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>