target: Add missing parentheses

Code like " &= ~CMD_T_BUSY | ..." only clears CMD_T_BUSY but not
the other flag. Modify these statements such that both flags are
cleared.

(Fix fuzz for target_write_prot_action code in mainline - nab)

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>