isdn: sc: work around type mismatch warning

This driver shows warnings on many architectures:

drivers/isdn/sc/init.c: In function 'identify_board':
drivers/isdn/sc/init.c:484:2: error: passing argument 1 of 'readl' makes pointer from integer without a cast [-Werror]

In newer kernels, it was completely removed, but for the 4.4-stable
series, let's just shut up that warning by adding an extra variable
to do the necessary type cast.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/isdn/sc/init.c

@@ -441,6 +441,7 @@ static int identify_board(unsigned long rambase, unsigned int iobase)
 	RspMessage rcvmsg;
 	ReqMessage sndmsg;
 	HWConfig_pl hwci;
+	void __iomem *rambase_sig = (void __iomem *)rambase + SIG_OFFSET;
 	int x;
 
 	pr_debug("Attempting to identify adapter @ 0x%lx io 0x%x\n",
@@ -481,7 +482,7 @@ static int identify_board(unsigned long rambase, unsigned int iobase)
 	 */
 	outb(PRI_BASEPG_VAL, pgport);
 	msleep_interruptible(1000);
-	sig = readl(rambase + SIG_OFFSET);
+	sig = readl(rambase_sig);
 	pr_debug("Looking for a signature, got 0x%lx\n", sig);
 	if (sig == SIGNATURE)
 		return PRI_BOARD;
@@ -491,7 +492,7 @@ static int identify_board(unsigned long rambase, unsigned int iobase)
 	 */
 	outb(BRI_BASEPG_VAL, pgport);
 	msleep_interruptible(1000);
-	sig = readl(rambase + SIG_OFFSET);
+	sig = readl(rambase_sig);
 	pr_debug("Looking for a signature, got 0x%lx\n", sig);
 	if (sig == SIGNATURE)
 		return BRI_BOARD;
@@ -501,7 +502,7 @@ static int identify_board(unsigned long rambase, unsigned int iobase)
 	/*
 	 * Try to spot a card
 	 */
-	sig = readl(rambase + SIG_OFFSET);
+	sig = readl(rambase_sig);
 	pr_debug("Looking for a signature, got 0x%lx\n", sig);
 	if (sig != SIGNATURE)
 		return -1;