omap3: cm-t35: move get_board_serial() fallback

The fallback is used for cases when CONFIG_SERIAL_TAG defined, but the
eeprom is not used.
The fallback is useful for more than one CompuLab board, so move it to a
common location.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Reviewed-by: Tom Rini <trini@ti.com>

board/compulab/cm_t35/cm_t35.c

@@ -457,16 +457,6 @@ int board_eth_init(bd_t *bis)
 }
 #endif
 
-void __weak get_board_serial(struct tag_serialnr *serialnr)
-{
-	/*
-	 * This corresponds to what happens when we can communicate with the
-	 * eeprom but don't get a valid board serial value.
-	 */
-	serialnr->low = 0;
-	serialnr->high = 0;
-};
-
 #ifdef CONFIG_USB_EHCI_OMAP
 struct omap_usbhs_board_data usbhs_bdata = {
 	.port_mode[0] = OMAP_EHCI_PORT_MODE_PHY,

board/compulab/common/common.c

@@ -25,6 +25,18 @@ void cl_print_pcb_info(void)
 	printf("PCB:   %u.%u\n", rev_major, rev_minor);
 }
 
+#ifdef CONFIG_SERIAL_TAG
+void __weak get_board_serial(struct tag_serialnr *serialnr)
+{
+	/*
+	 * This corresponds to what happens when we can communicate with the
+	 * eeprom but don't get a valid board serial value.
+	 */
+	serialnr->low = 0;
+	serialnr->high = 0;
+};
+#endif
+
 #ifdef CONFIG_CMD_USB
 int cl_usb_hub_init(int gpio, const char *label)
 {