ide: move drive_is_ready() to ide-io.c

Move drive_is_ready() to ide-io.c, then make it static.

Also make some minor CodingStyle fixups while at it.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>