Add Board Revision for Wireless chip

Gumstix Overo COMs with board revision 0x4 use a different Wifi and
Bluetooth module: Wi2Wi's W2CBW0015.  No other code changes are required
in u-boot---just handling of this particular board revision.

Signed-off-by: Ash Charles <ashcharles@gmail.com>

board/overo/overo.c

@@ -141,6 +141,7 @@ void get_board_mem_timings(struct board_sdrc_timings *timings)
 		timings->rfr_ctrl = SDP_3430_SDRC_RFR_CTRL_165MHz;
 		break;
 	case REVISION_1: /* Micron 256MB/512MB, 1/2 banks of 256MB */
+	case REVISION_4:
 		timings->mcfg = MICRON_V_MCFG_200(256 << 20);
 		timings->ctrla = MICRON_V_ACTIMA_200;
 		timings->ctrlb = MICRON_V_ACTIMB_200;

board/overo/overo.h

@@ -22,6 +22,7 @@ const omap3_sysinfo sysinfo = {
 #define REVISION_1	0x1
 #define REVISION_2	0x2
 #define REVISION_3	0x3
+#define REVISION_4	0x4
 
 /*
  * IEN  - Input Enable