lib/Kconfig.debug: fix typo in the help text of CONFIG_PANIC_TIMEOUT

There exists duplicated "the" in the help text of CONFIG_PANIC_TIMEOUT,
Remove it.
Signed-off-by: NTiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Link: http://lkml.kernel.org/r/1591103358-32087-2-git-send-email-yangtiezhu@loongson.cnSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig.debug

@@ -917,7 +917,7 @@ config PANIC_TIMEOUT
 	int "panic timeout"
 	default 0
 	help
-	  Set the timeout value (in seconds) until a reboot occurs when the
+	  Set the timeout value (in seconds) until a reboot occurs when
 	  the kernel panics. If n = 0, then we wait forever. A timeout
 	  value n > 0 will wait n seconds before rebooting, while a timeout
 	  value n < 0 will reboot immediately.