net/fec: consolidate all i.MX options to CONFIG_ARM

Moreover stop listing all i.MX platforms featuring a FEC, and use
the platform's config symbol that selects registration of a fec device
instead.  This might make it easier to add new platforms.

Set default = y for ARMs having a fec to reduce defconfig sizes.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
diff --git a/drivers/net/fec.c b/drivers/net/fec.c
index 14eb660..dd4e580 100644
--- a/drivers/net/fec.c
+++ b/drivers/net/fec.c
@@ -54,7 +54,7 @@
 
 #include "fec.h"
 
-#if defined(CONFIG_ARCH_MXC) || defined(CONFIG_SOC_IMX28)
+#if defined(CONFIG_ARM)
 #define FEC_ALIGNMENT	0xf
 #else
 #define FEC_ALIGNMENT	0x3
@@ -147,8 +147,7 @@
  * account when setting it.
  */
 #if defined(CONFIG_M523x) || defined(CONFIG_M527x) || defined(CONFIG_M528x) || \
-    defined(CONFIG_M520x) || defined(CONFIG_M532x) || \
-    defined(CONFIG_ARCH_MXC) || defined(CONFIG_SOC_IMX28)
+    defined(CONFIG_M520x) || defined(CONFIG_M532x) || defined(CONFIG_ARM)
 #define	OPT_FRAME_SIZE	(PKT_MAXBUF_SIZE << 16)
 #else
 #define	OPT_FRAME_SIZE	0