Build smbios.ko as a module for amd64 and i386

[rpokala]

Summary

For whatever reason, smapi, smbios, vpd are all under the "bios" directory.
smapi is only for i386, so the entire "bios" directory is only built for
i386. Break smapi out, and make only it i386-specific. Then, build the
"bios" directory for both amd64 and i386.

Test Plan

make tinderbox
find ${MAKEOBJDIRPREFIX} -name smbios.ko -o -name vpd.ko -o -name smapi.ko | egrep '/GENERIC/'

Before: All three are present for i386.i386, and none are present for any other platform.

After: All three are present for i386.i386 and pc98.i386, and smbios.ko and vpd.ko are present for amd64.amd64.

[emaste]

As long as these modules work on amd64, seems reasonable!

[rpokala]

@imp approved this on IRC last night:

19:24:34 rpokala: bsdimp: if you're around, please review D8609 when you have a sec
19:24:36 rpokala: thanks!
19:24:55 bsdimp: k
19:26:45 bsdimp: rpokala, looks great.
19:26:51 bsdimp: rpokala, I can't login.
19:28:20 rpokala: bsdimp: well foo
19:28:58 rpokala: i gotta head home anyway; if you can figure it out, great; if not, i'll note that you approved it "verbally" and check it in when i get home
19:29:08 rpokala: thanks!

Marking this "accepted" on his behalf.