fbdev: matrox: fix -Wextra build warnings

When 'DEBUG' is not defined, modify the dprintk() macro to use the
no_printk() macro instead of using <empty>.
This fixes build warnings when -Wextra is used and provides
printk format checking:

../drivers/video/fbdev/matrox/matroxfb_base.c:635:77: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
../drivers/video/fbdev/matrox/matroxfb_Ti3026.c:632:54: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body]
../drivers/video/fbdev/matrox/matroxfb_Ti3026.c:654:53: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body]

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: Antonino Daplas <[e-mail]>
Cc: Florian Tobias Schandinat <[e-mail]>
Signed-off-by: Bartlomiej Zolnierkiewicz <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/matrox/matroxfb_base.h

···
 #ifdef DEBUG
 #define dprintk(X...)	printk(X)
 #else
-#define dprintk(X...)
+#define dprintk(X...)	no_printk(X)
 #endif
 
 #ifndef PCI_SS_VENDOR_ID_SIEMENS_NIXDORF