[PATCH] parport: fix if-statement empty body warnings

[Randy Dunlap]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

When debugging via DPRINTK() is not enabled, make the DPRINTK()
macro be an empty do-while block.

This fixes gcc warnings when -Wextra is set:

../drivers/parport/ieee1284.c:262:18: warning: suggest braces around empty body in an âifâ statement [-Wempty-body]
../drivers/parport/ieee1284.c:285:17: warning: suggest braces around empty body in an âifâ statement [-Wempty-body]
../drivers/parport/ieee1284.c:298:17: warning: suggest braces around empty body in an âifâ statement [-Wempty-body]
../drivers/parport/ieee1284_ops.c:576:18: warning: suggest braces around empty body in an âifâ statement [-Wempty-body]

I have verified that there is no object code change (with gcc 7.5.0).

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Cc: Sudip Mukherjee <sudip.mukherjee@xxxxxxxxxxxxxxx>
Cc: linux-parport@xxxxxxxxxxxxxxxxxxx
---
 drivers/parport/ieee1284.c     |    2 +-
 drivers/parport/ieee1284_ops.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- linux-next-20200225.orig/drivers/parport/ieee1284.c
+++ linux-next-20200225/drivers/parport/ieee1284.c
@@ -34,7 +34,7 @@
 #ifdef DEBUG
 #define DPRINTK(stuff...) printk (stuff)
 #else
-#define DPRINTK(stuff...)
+#define DPRINTK(stuff...) do {} while (0)
 #endif
 
 /* Make parport_wait_peripheral wake up.
--- linux-next-20200225.orig/drivers/parport/ieee1284_ops.c
+++ linux-next-20200225/drivers/parport/ieee1284_ops.c
@@ -30,7 +30,7 @@
 #ifdef DEBUG
 #define DPRINTK(stuff...) printk (stuff)
 #else
-#define DPRINTK(stuff...)
+#define DPRINTK(stuff...) do {} while (0)
 #endif
 
 /***                                *