Gpudev

[PeterDinda]

• Please check if the request fulfills these requirements

• [X] The commit messages follow our guidelines (See Contributing).

• [X] The code follows our style guidelines, again see Contributing.

• [X] If this is a new feature, changes to the core kernel have been minimized.

• [X] If this feature doesn't touch the core kernel, has it been properly separated out in the Kconfig? and the source tree?

• [ ] If this pull request is for an open issue, the issue is properly referenced.

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Adds a 2D graphics device layer

• What is the current behavior? (You can also link to an open issue here)

There is no graphics device layer

• What is the new behavior (if this is a feature change)?

There is one now.

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

The gpudev layer is initialized at boot time, but this should be minor, like the other device layers

• Other information:

[PeterDinda]

Merging this because it's in good shape and there is no external dependence except for an init() for this class of devices.