lib: smbios: Let detect the system via sysinfo

lib: smbios: Let detect the system via sysinfo

Currently code looks like that it sysinfo drivers are supported but
actually none checking that system is detected. That's why call
sysinfo_detect() to make sure that priv->detected in sysinfo uclass is
setup hence information from driver can be passed to smbios.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Simon Glass <sjg@chromium.org>