mb/google/volteer: Add probed fw_configs to SMBIOS OEM strings

mb/google/volteer: Add probed fw_configs to SMBIOS OEM strings

Some Linux kernel drivers bind to "DMI quirks." In this case, the audio
fw_config is added as an OEM string, e.g., "AUDIO-MAX98357_ALC5682I_I2S"
so the audio topology can be correctly discovered.
But add all successfully probed fw_config items as well, because this
makes it easier to view what is selected from userspace.

BUG=b:161963281
TEST=With CBI FW_CONFIG field set to 0x201:

localhost ~ # dmidecode -t 11
# dmidecode 3.2
Getting SMBIOS data from sysfs.
SMBIOS 3.0 present.

Handle 0x0009, DMI type 11, 5 bytes
OEM Strings
        String 1: DB_USB-USB4_GEN2
        String 2: AUDIO-MAX98373_ALC5682I_I2S

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I7b7586b0ebfe7b2fd888f448a50ae086364fa718
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44783
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>