MIPS: TXx9: CONFIG_TOSHIBA_RBTX4939 spelling

Fix a typo in the comment for the TOSHIBA_RBTX4939 config option
Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Acked-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/txx9/Kconfig

@@ -46,7 +46,7 @@ config TOSHIBA_RBTX4938
 	  support this machine type
 
 config TOSHIBA_RBTX4939
-	bool "Toshiba RBTX4939 bobard"
+	bool "Toshiba RBTX4939 board"
 	depends on MACH_TX49XX
 	select SOC_TX4939
 	select TXX9_7SEGLED