After replacing of include/config/auto.conf sourcing with
extraction of CONFIG_LOCALVERSION, resulting version string
contains quotes around localversion part which are always
present in auto.conf (even if localversion is empty).

This patch fixes this script to remove quotes.

Signed-off-by: Nikita Maslov <wkernelteam@gmail.com>
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>