firmware: dmi_scan: Simplified displayed version

The trailing .x adds no information for the reader, and if anyone
tries to parse that line, this is more work as they have 3 different
formats to handle instead of 2. Plus, this makes backporting fixes
harder.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Fixes: 95be58df ("firmware: dmi_scan: Use full dmi version for SMBIOS3")
Cc: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>