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.

Change-Id: I5c93e458e2f7205b69ffef473ac7154a675fc9bd
Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: 68e6f221ed0 ("block: ide: Fix block read/write with driver model")