ide: Use a single local blk_desc for ide_ident()

We only use one member of the ide_dev_desc[] array at a time and it does
not stick around outside ide_probe(). Use a single element instead.

Copy over the missing members of blk_desc at the same, since this was
missing from the previous code.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: 68e6f221 ("block: ide: Fix block read/write with driver model")