MIPS: Sibyte: Export symbol periph_rev to sb1250-mac network driver.

This fixes the following modpost error:

ERROR: "periph_rev" [drivers/net/ethernet/broadcom/sb1250-mac.ko] undefined!
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/sibyte/bcm1480/setup.c

@@ -36,6 +36,7 @@ unsigned int soc_pass;
 unsigned int soc_type;
 EXPORT_SYMBOL(soc_type);
 unsigned int periph_rev;
+EXPORT_SYMBOL_GPL(periph_rev);
 unsigned int zbbus_mhz;
 EXPORT_SYMBOL(zbbus_mhz);
 

arch/mips/sibyte/sb1250/setup.c

@@ -34,6 +34,7 @@ unsigned int soc_pass;
 unsigned int soc_type;
 EXPORT_SYMBOL(soc_type);
 unsigned int periph_rev;
+EXPORT_SYMBOL_GPL(periph_rev);
 unsigned int zbbus_mhz;
 EXPORT_SYMBOL(zbbus_mhz);