nvdimm: Remove usage of the deprecated ida_simple_xx() API

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

This is less verbose.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/50719568e4108f65f3b989ba05c1563e17afba3f.1702228319.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Ira Weiny <ira.weiny@intel.com>