ide: Correct LBA setting

Fix a longstanding bug where the LBA is calculated as the size of the
media instead of the number of blocks. This was perhaps not noticed
earlier since it prints the correct value first, before setting the wrong
value.

Drop the unnecessary blksz variable while we are here.

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