Fuchsia SDK

These files are copied from the Fuchsia build. See https://cs.opensource.google/fuchsia/fuchsia/+/master:src/firmware/.

VIM3 Modifications

The Firmware SDK doesn't build cleanly in the VIM3 u-boot repo, mostly due to a few compiler flag and header name differences.

To help make it easier to uprev the Firmware SDK, there is a patch file here that modifies the Firmware SDK files for VIM3.

To uprev:

cd into the VIM3 u-boot root
start a new branch

copy the new Firmware SDK over, for example something like:

$ rsync -r --copy-links <fuchsia_out>/sdk/exported/firmware/ lib/fuchsia/firmware_sdk/

# Remove the stuff we don't care about for VIM3.
$ rm -rf lib/fuchsia/firmware_sdk/{obj,arch/riscv64,arch/x64}

commit the change
```
$ git add .
$ git commit
```
optional: you may want to upload the CL to Gerrit at this point with the raw SDK files. It won't be submitted but it can be useful to have the first patch set be the unmodified SDK files for easier diffs with the final result
apply the patch (this will create a second change in the stack):
```
$ git am -3 lib/fuchsia/vim3_firmware_sdk_fixup.patch
```
if the patch doesn't apply cleanly:
1. fix any merge conflicts
2. commit
3. update the .patch file:
```
$ git format-patch --stdout HEAD~1 lib/ >lib/fuchsia/vim3_firmware_sdk_fixup.patch
```
4. add the updated .patch file to the commit
merge the uprev and patch CLs