[MIPS] Mention Broadcom part number for BigSur board

    
Mention the Broadcom part number for the BigSur board (BCM91480B)
in Kconfig, just like it's done for other Broadcom boards.
Signed-off-by: NMartin Michlmayr <tbm@cyrius.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -602,7 +602,7 @@ config SGI_IP32
 	  If you want this kernel to run on SGI O2 workstation, say Y here.
 
 config SIBYTE_BIGSUR
-	bool "Support for Sibyte BigSur"
+	bool "Support for Sibyte BCM91480B-BigSur"
 	select BOOT_ELF32
 	select DMA_COHERENT
 	select PCI_DOMAINS