ide-cd: fix endianity for the error message in cdrom_read_capacity

Aesthetic regards aside, commit e8e7b9eb
still leaves a bug in the error message, because it uses the unconverted
big-endian value for printk.

Fix this by using a local variable in machine byte order. The result is
correct, more readable, and also produces slightly shorter code on i386.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org>
Acked-by: Borislav Petkov <petkovbb@gmail.com>
[bart: __u32 -> u32]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>