dw-xdata: 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/cc01721cec2d416d7bdf47086943b17ef44b7286.1702966181.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>