ide-cd: fold cdrom_start_seek into ide_cd_do_request

Do what the compiler does anyway: inline a function that is used only once.

This saves us the overhead of a function call and the function is small enough
to be embedded in the callsite anyways.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>