[SCSI] megaraid: Make megaraid_ioctl() check copy_to_user() return value

Check copy_to_user() return value in drivers/scsi/megaraid.c::megadev_ioctl()
This gets rid of this little warning:
  drivers/scsi/megaraid.c:3661: warning: ignoring return value of 'copy_to_user', declared with attribute warn_unused_result

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Acked-by: "Ju, Seokmann" <Seokmann.Ju@lsil.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>