payloads/seabios: Update version number in Kconfig

Fix up commit 4f66648c (payloads/seabios: Upgrade stable from 1.9.0 to
1.9.1), forgetting to update the version number displayed in the Kconfig
menu, by updating the string to 1.9.1.

Change-Id: Idb395d0ea65bcf91c7c9645fd76d428936e91587
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: https://review.coreboot.org/14010
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)
1 file changed