tty/serial/8250: fix typo in help text

Commit 9326b047e4fd4a8da72e59d913214a1803e9709c includes a typo
of "8350_core" instead of "8250_core", so correct it.

Fixes kernel bugzilla #60724:
  https://bugzilla.kernel.org/show_bug.cgi?id=60724

Reported-by: Christoph Biedl <bugzilla.kernel.bpeb@manchmal.in-ulm.de>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/Kconfig

@@ -41,7 +41,7 @@ config SERIAL_8250_DEPRECATED_OPTIONS
 	  accept kernel parameters in both forms like 8250_core.nr_uarts=4 and
 	  8250.nr_uarts=4. We now renamed the module back to 8250, but if
 	  anybody noticed in 3.7 and changed their userspace we still have to
-	  keep the 8350_core.* options around until they revert the changes
+	  keep the 8250_core.* options around until they revert the changes
 	  they already did.
 
 	  If 8250 is built as a module, this adds 8250_core alias instead.