net/can/mscan: replace hardcoded values with defines

Not all hardcoded values have been replaced as this made the code quite
unreadable. IMHO this compromise serves the purpose of readability.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/can/mscan/mscan.h b/drivers/net/can/mscan/mscan.h
index 2018000..00fc4aa 100644
--- a/drivers/net/can/mscan/mscan.h
+++ b/drivers/net/can/mscan/mscan.h
@@ -131,6 +131,11 @@
 /* MSCAN Miscellaneous Register (CANMISC) bits */
 #define MSCAN_BOHOLD		0x01
 
+/* MSCAN Identifier Register (IDR) bits */
+#define MSCAN_SFF_RTR_SHIFT	4
+#define MSCAN_EFF_RTR_SHIFT	0
+#define MSCAN_EFF_FLAGS		0x18	/* IDE + SRR */
+
 #ifdef MSCAN_FOR_MPC5200
 #define _MSCAN_RESERVED_(n, num) u8 _res##n[num]
 #define _MSCAN_RESERVED_DSR_SIZE	2