MFD: mcp-core: fix mcp_priv() to be more type safe

mcp_priv() does unexpected things when passed a void pointer.  Make it
a typed inline function, which ensures that it works correctly in
these cases.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

include/linux/mfd/mcp.h

@@ -64,6 +64,9 @@ void mcp_driver_unregister(struct mcp_driver *);
 #define mcp_get_drvdata(mcp)	dev_get_drvdata(&(mcp)->attached_device)
 #define mcp_set_drvdata(mcp,d)	dev_set_drvdata(&(mcp)->attached_device, d)
 
-#define mcp_priv(mcp)		((void *)((mcp)+1))
+static inline void *mcp_priv(struct mcp *mcp)
+{
+	return mcp + 1;
+}
 
 #endif