smbios: Fix wrong sysinfo ID for Type 3 enclosure asset tag

smbios_write_type3() uses SYSID_SM_BASEBOARD_ASSET_TAG (Type 2) instead
of SYSID_SM_ENCLOSURE_ASSET_TAG (Type 3) for the enclosure asset tag.
This causes the enclosure's asset tag to be read from the baseboard
sysinfo field rather than the enclosure-specific one.

Fixes: bcf456dd ("smbios: add detailed smbios information")

Signed-off-by: Frank Böwingloh <f.boewingloh@beckhoff.com>
Cc: Raymond Mao <raymondmaoca@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Raymond Mao <raymondmaoca@gmail.com>