isdn: hisax: Merge Kconfig ifs

The first half of the HiSax config options is presented if
ISDN_DRV_HISAX!=n, while the second half of the options is presented
if ISDN_DRV_HISAX. That's the same, so merge both conditionals.
Signed-off-by: NJean Delvare <jdelvare@suse.de>
Cc: Karsten Keil <isdn@linux-pingi.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/hisax/Kconfig

@@ -16,7 +16,7 @@ config ISDN_DRV_HISAX
 	  also to the configuration option of the driver for your particular
 	  card, below.
 
-if ISDN_DRV_HISAX!=n
+if ISDN_DRV_HISAX
 
 comment "D-channel protocol features"
 
@@ -348,10 +348,6 @@ config HISAX_ENTERNOW_PCI
 	  This enables HiSax support for the Formula-n enter:now PCI
 	  ISDN card.
 
-endif
-
-if ISDN_DRV_HISAX
-
 config HISAX_DEBUG
 	bool "HiSax debugging"
 	help