ide: add PC_FLAG_DRQ_INTERRUPT pc flag

Add PC_FLAG_DRQ_INTERRUPT pc flag, set it in ide*_do_request()
and check for it (instead of checking for IDE*_FLAG_DRQ_INTERRUPT)
in ide*_issue_pc().  This is a preparation for adding generic
ide_issue_pc() helper.

There should be no functional changes caused by this patch.

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

include/linux/ide.h

@@ -608,6 +608,7 @@ enum {
 	/* command timed out */
 	PC_FLAG_TIMEDOUT		= (1 << 7),
 	PC_FLAG_ZIP_DRIVE		= (1 << 8),
+	PC_FLAG_DRQ_INTERRUPT		= (1 << 9),
 };
 
 struct ide_atapi_pc {