misc: pci_endpoint_test: Remove usage of the deprecated ida_simple_*() API

ida_alloc() and ida_free() should be preferred to the deprecated
ida_simple_get() and ida_simple_remove() functions.

This is also less verbose.

Link: https://lore.kernel.org/linux-pci/47a30441242c4d5f0e00555cbddd7783350ff1b2.1702966523.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>