scsi: pmcraid: use normal copy_from_user

As pointed out by Al Viro for my previous series, the driver has no need
to call access_ok() and __copy_from_user()/__copy_to_user(). Changing
it to regular copy_from_user()/copy_to_user() simplifies the code without
any real downsides, making it less error-prone at best.

This patch by itself also addresses the warning about the access_ok()
macro on MIPS, but both fixes improve the code, so ideally we apply
them both.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>