PCI: endpoint: pci-epf-vntb: Remove superfluous checks for pci_epf_alloc_space() API

PCI: endpoint: pci-epf-vntb: Remove superfluous checks for pci_epf_alloc_space() API

Now that the checks are performed by the pci_epf_alloc_space() API, let's
remove the superfluous checks in this driver.

Signed-off-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20240207213922.1796533-5-cassel@kernel.org
[mani: reworded the commit message]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>